Abstract

The comparison of optical atomic clocks with frequency instabilities reaching 1 part in 1016 at 1 s will enable more stringent tests of fundamental physics. These comparisons, mediated by optical frequency combs, require optical synthesis and measurement with a performance better than, or comparable to, the best optical clocks. Fiber-based mode-locked lasers have shown great potential for compact, robust, and efficient optical clockwork but typically require multiple amplifier and fiber optic paths that limit the achievable fractional frequency stability near 1 part in 1016 at 1 s. Here we describe an erbium-fiber laser frequency comb that overcomes these conventional challenges by ensuring that all critical fiber paths are common mode and within the servo-controlled feedback loop. Using this architecture, we demonstrate a fractional optical measurement uncertainty below 1×1019 and fractional frequency instabilities less than 3×1018 at 1 s and 1×1019 at 1000 s.

© 2017 Optical Society of America

Full Article  |  PDF Article
OSA Recommended Articles
Ultra-broadband dual-branch optical frequency comb with 10−18 instability

Antoine Rolland, Peng Li, Naoya Kuse, Jie Jiang, Marco Cassinerio, Carsten Langrock, and Martin E. Fermann
Optica 5(9) 1070-1077 (2018)

Direct phase-locking of a Ti:Sapphire optical frequency comb to a remote optical frequency standard

Eunmi Chae, Kota Nakashima, Takuya Ikeda, Kei Sugiyama, and Kosuke Yoshioka
Opt. Express 27(11) 15649-15661 (2019)

A multi-branch, fiber-based frequency comb with millihertz-level relative linewidths using an intra-cavity electro-optic modulator

Yoshiaki Nakajima, Hajime Inaba, Kazumoto Hosaka, Kaoru Minoshima, Atsushi Onae, Masami Yasuda, Takuya Kohno, Sakae Kawato, Takao Kobayashi, Toshio Katsuyama, and Feng-Lei Hong
Opt. Express 18(2) 1667-1676 (2010)

References

  • View by:
  • |
  • |
  • |

  1. B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506, 71–75 (2014).
    [Crossref]
  2. N. Hinkley, J. A. Sherman, N. B. Phillips, M. Schioppo, N. D. Lemke, K. Beloy, M. Pizzocaro, C. W. Oates, and A. D. Ludlow, “An atomic clock with 10−18 instability,” Science 341, 1215–1218 (2013).
    [Crossref]
  3. M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
    [Crossref]
  4. T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
    [Crossref]
  5. T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
    [Crossref]
  6. T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
    [Crossref]
  7. N. Huntemann, B. Lipphardt, C. Tamm, V. Gerginov, S. Weyers, and E. Peik, “Improved limit on a temporal variation of mp/me from comparisons of Yb+ and Cs atomic clocks,” Phys. Rev. Lett. 113, 210802 (2014).
    [Crossref]
  8. M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
    [Crossref]
  9. R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
    [Crossref]
  10. C. W. Chou, D. B. Hume, T. Rosenband, and D. J. Wineland, “Optical clocks and relativity,” Science 329, 1630–1633 (2010).
    [Crossref]
  11. S. Kolkowitz, I. Pikovski, N. Langellier, M. D. Lukin, R. L. Walsworth, and J. Ye, “Gravitational wave detection with optical lattice atomic clocks,” Phys. Rev. D 94, 124043 (2016).
    [Crossref]
  12. A. Derevianko and M. Pospelov, “Hunting for topological dark matter with atomic clocks,” Nat. Phys. 10, 933–936 (2014).
    [Crossref]
  13. T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
    [Crossref]
  14. M. Takamoto, F.-L. Hong, R. Higashi, and H. Katori, “An optical lattice clock,” Nature 435, 321–324 (2005).
    [Crossref]
  15. H. S. Margolis, G. P. Barwood, G. Huang, H. A. Klein, S. N. Lea, K. Szymaniec, and P. Gill, “Hertz-level measurement of the optical clock frequency in a single 88Sr+ ion,” Science 306, 1355–1358 (2004).
    [Crossref]
  16. S. A. Diddams, “The evolving optical frequency comb,” J. Opt. Soc. Am. B 27, B51–B62 (2010).
    [Crossref]
  17. F. Adler, P. Masłowski, A. Foltynowicz, K. C. Cossel, T. C. Briles, I. Hartl, and J. Ye, “Mid-infrared Fourier transform spectroscopy with a broadband frequency comb,” Opt. Express 18, 21861–21872 (2010).
    [Crossref]
  18. M. J. Thorpe, K. D. Moll, R. J. Jones, B. Safdi, and J. Ye, “Broadband cavity ringdown spectroscopy for sensitive and rapid molecular detection,” Science 311, 1595–1599 (2006).
    [Crossref]
  19. T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
    [Crossref]
  20. G. G. Ycas, F. Quinlan, S. A. Diddams, S. Osterman, S. Mahadevan, S. Redman, R. Terrien, L. Ramsey, C. F. Bender, B. Botzer, and S. Sigurdsson, “Demonstration of on-sky calibration of astronomical spectra using a 25  GHz near-IR laser frequency comb,” Opt. Express 20, 6631–6643 (2012).
    [Crossref]
  21. T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
    [Crossref]
  22. J. Millo, R. Boudot, M. Lours, P. Y. Bourgeois, A. N. Luiten, Y. L. Coq, Y. Kersalé, and G. Santarelli, “Ultra-low-noise microwave extraction from fiber-based optical frequency comb,” Opt. Lett. 34, 3707–3709 (2009).
    [Crossref]
  23. F. R. Giorgetta, W. C. Swann, L. C. Sinclair, E. Baumann, I. Coddington, and N. R. Newbury, “Optical two-way time and frequency transfer over free space,” Nat. Photonics 7, 434–438 (2013).
    [Crossref]
  24. J. Ye, J. L. Peng, R. J. Jones, K. W. Holman, J. L. Hall, D. J. Jones, S. A. Diddams, J. Kitching, S. Bize, J. C. Bergquist, L. W. Hollberg, L. Robertsson, and L. S. Ma, “Delivery of high-stability optical and microwave frequency standards over an optical fiber network,” J. Opt. Soc. Am. B 20, 1459–1467 (2003).
    [Crossref]
  25. K. Jung, J. Shin, J. Kang, S. Hunziker, C. K. Min, and J. Kim, “Frequency comb-based microwave transfer over fiber with 7 x 10−19 instability using fiber-loop optical-microwave phase detectors,” Opt. Lett. 39, 1577–1580 (2014).
    [Crossref]
  26. S. M. Foreman, K. W. Holman, D. D. Hudson, D. J. Jones, and J. Ye, “Remote transfer of ultrastable frequency references via fiber networks,” Rev. Sci. Instrum. 78, 021101 (2007).
    [Crossref]
  27. S. Droste, F. Ozimek, T. Udem, K. Predehl, T. W. Hansch, H. Schnatz, G. Grosche, and R. Holzwarth, “Optical-frequency transfer over a single-span 1840  km fiber link,” Phys. Rev. Lett. 111, 110801 (2013).
    [Crossref]
  28. I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
    [Crossref]
  29. J. Kim, J. A. Cox, J. Chen, and F. X. Kartner, “Drift-free femtosecond timing synchronization of remote optical and microwave sources,” Nat. Photonics 2, 733–736 (2008).
    [Crossref]
  30. J. F. Cliche, B. Shillue, C. Latrasse, M. Tetu, and L. D’Addario, “A high coherence, high stability laser for the photonic local oscillator distribution of the Atacama Large Millimeter Array,” in Ground-Based Telescopes, Parts 1 and 2, J. M. Oschmann, ed. (2004), pp. 1115–1126.
  31. N. R. Nand, J. G. Hartnett, E. N. Ivanov, and G. Santarelli, “Ultra-stable very-low phase-noise signal source for very long baseline interferometry using a cryocooled sapphire oscillator,” IEEE Trans. Microw. Theory Tech. 59, 2978–2986 (2011).
    [Crossref]
  32. G. D. Cole, W. Zhang, M. J. Martin, J. Ye, and M. Aspelmeyer, “Tenfold reduction of Brownian noise in high-reflectivity optical coatings,” Nat. Photonics 7, 644–650 (2013).
    [Crossref]
  33. T. Kessler, C. Hagemann, C. Grebing, T. Legero, U. Sterr, F. Riehle, M. J. Martin, L. Chen, and J. Ye, “A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity,” Nat. Photonics 6, 687–692 (2012).
    [Crossref]
  34. D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).
  35. L. C. Sinclair, I. Coddington, W. C. Swann, G. B. Rieker, A. Hati, K. Iwakuni, and N. R. Newbury, “Operation of an optically coherent frequency comb outside the metrology lab,” Opt. Express 22, 6996–7006 (2014).
    [Crossref]
  36. N. Kuse, J. Jiang, C.-C. Lee, T. Schibli, and M. Fermann, “All polarization-maintaining Er fiber-based optical frequency combs with nonlinear amplifying loop mirror,” Opt. Express 24, 3095–3102 (2016).
    [Crossref]
  37. M. Lezius, T. Wilken, C. Deutsch, M. Giunta, O. Mandel, A. Thaller, V. Schkolnik, M. Schiemangk, A. Dinkelaker, and A. Kohfeldt, “Space-borne frequency comb metrology,” Optica 3, 1381–1387 (2016).
    [Crossref]
  38. J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
    [Crossref]
  39. L. S. Ma, Z. Y. Bi, A. Bartels, L. Robertsson, M. Zucco, R. S. Windeler, G. Wilpers, C. Oates, L. Hollberg, and S. A. Diddams, “Optical frequency synthesis and comparison with uncertainty at the 10−19 level,” Science 303, 1843–1845 (2004).
    [Crossref]
  40. Y. Yao, Y. Jiang, H. Yu, Z. Bi, and L. Ma, “Optical frequency divider with division uncertainty at the 10−21 level,” Natl. Sci. Rev. 3, 463–469 (2016).
    [Crossref]
  41. C. Hagemann, C. Grebing, T. Kessler, S. Falke, N. Lemke, C. Lisdat, H. Schnatz, F. Riehle, and U. Sterr, “Providing short-term stability of a 1.5-laser to optical clocks,” IEEE Trans. Instrum. Meas. 62, 1556–1562 (2013).
    [Crossref]
  42. H. Inaba, Y. Daimon, F. L. Hong, A. Onae, K. Minoshima, T. R. Schibli, H. Matsumoto, M. Hirano, T. Okuno, M. Onishi, and M. Nakazawa, “Long-term measurement of optical frequencies using a simple, robust and low-noise fiber based frequency comb,” Opt. Express 14, 5223–5231 (2006).
    [Crossref]
  43. Y. Nakajima, H. Inaba, K. Hosaka, K. Minoshima, A. Onae, M. Yasuda, T. Kohno, S. Kawato, T. Kobayashi, and T. Katsuyama, “A multi-branch, fiber-based frequency comb with millihertz-level relative linewidths using an intra-cavity electro-optic modulator,” Opt. Express 18, 1667–1676 (2010).
    [Crossref]
  44. I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, “Cryogenic optical lattice clocks,” Nat. Photonics 9, 185–189 (2015).
    [Crossref]
  45. N. Ohmae, N. Kuse, M. Fermann, and H. Katori, “All-polarization-maintaining, single-port Er:fiber comb for high-stability comparison of optical lattice clocks,” Appl. Phys. Express 10, 062503 (2017).
    [Crossref]
  46. D. Nicolodi, B. Argence, W. Zhang, R. Le Targat, G. Santarelli, and Y. Le Coq, “Spectral purity transfer between optical wavelengths at the 10−18 level,” Nat. Photonics 8, 219–223 (2014).
    [Crossref]
  47. L. E. Nelson, D. J. Jones, K. Tamura, H. A. Haus, and E. P. Ippen, “Ultrashort-pulse fiber ring lasers,” Appl. Phys. B 65, 277–294 (1997).
    [Crossref]
  48. T. Okuno, M. Onishi, T. Kashiwada, S. Ishikawa, and M. Nishimura, “Silica-based functional fibers with enhanced nonlinearity and their applications,” IEEE J. Sel. Top. Quantum Electron. 5, 1385–1391 (1999).
    [Crossref]
  49. M. J. Martin, S. M. Foreman, T. Schibli, and J. Ye, “Testing ultrafast mode-locking at microhertz relative optical linewidth,” Opt. Express 17, 558–568 (2009).
    [Crossref]
  50. J. Stenger, H. Schnatz, C. Tamm, and H. R. Telle, “Ultraprecise measurement of optical frequency ratios,” Phys. Rev. Lett. 88, 073601 (2002).
    [Crossref]
  51. D. B. Sullivan, D. W. Allan, D. A. Howe, and F. L. Walls, Characterization of Clocks and Oscillators (National Institute of Standards and Technology Technical Note, 1990).
  52. D. Yeaton-Massey and R. X. Adhikari, “A new bound on excess frequency noise in second harmonic generation in PPKTP at the 10−19 level,” Opt. Express 20, 21019–21024 (2012).
    [Crossref]
  53. M. Zimmermann, C. Gohle, R. Holzwarth, T. Udem, and T. W. Hänsch, “Optical clockwork with an offset-free difference-frequency comb: accuracy of sum-and difference-frequency generation,” Opt. Lett. 29, 310–312 (2004).
    [Crossref]
  54. S. T. Dawkins, J. J. McFerran, and A. N. Luiten, “Considerations on the measurement of the stability of oscillators with frequency counters,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 54, 918–925 (2007).
    [Crossref]
  55. T. M. Fortier, J. Ye, S. T. Cundiff, and R. S. Windeler, “Nonlinear phase noise generated in air–silica microstructure fiber and its effect on carrier–envelope phase,” Opt. Lett. 27, 445–447 (2002).
    [Crossref]
  56. L. Johnson, P. Gill, and H. Margolis, “Evaluating the performance of the NPL femtosecond frequency combs: agreement at the 10−21 level,” Metrologia 52, 62–71 (2015).
    [Crossref]
  57. T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
    [Crossref]
  58. S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
    [Crossref]
  59. L. S. Ma, P. Jungner, J. Ye, and J. L. Hall, “Delivering the same optical frequency at two places: accurate cancellation of phase noise introduced by an optical fiber or other time-varying path,” Opt. Lett. 19, 1777–1779 (1994).
    [Crossref]

2017 (2)

M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
[Crossref]

N. Ohmae, N. Kuse, M. Fermann, and H. Katori, “All-polarization-maintaining, single-port Er:fiber comb for high-stability comparison of optical lattice clocks,” Appl. Phys. Express 10, 062503 (2017).
[Crossref]

2016 (5)

Y. Yao, Y. Jiang, H. Yu, Z. Bi, and L. Ma, “Optical frequency divider with division uncertainty at the 10−21 level,” Natl. Sci. Rev. 3, 463–469 (2016).
[Crossref]

S. Kolkowitz, I. Pikovski, N. Langellier, M. D. Lukin, R. L. Walsworth, and J. Ye, “Gravitational wave detection with optical lattice atomic clocks,” Phys. Rev. D 94, 124043 (2016).
[Crossref]

T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
[Crossref]

N. Kuse, J. Jiang, C.-C. Lee, T. Schibli, and M. Fermann, “All polarization-maintaining Er fiber-based optical frequency combs with nonlinear amplifying loop mirror,” Opt. Express 24, 3095–3102 (2016).
[Crossref]

M. Lezius, T. Wilken, C. Deutsch, M. Giunta, O. Mandel, A. Thaller, V. Schkolnik, M. Schiemangk, A. Dinkelaker, and A. Kohfeldt, “Space-borne frequency comb metrology,” Optica 3, 1381–1387 (2016).
[Crossref]

2015 (3)

L. Johnson, P. Gill, and H. Margolis, “Evaluating the performance of the NPL femtosecond frequency combs: agreement at the 10−21 level,” Metrologia 52, 62–71 (2015).
[Crossref]

T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
[Crossref]

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, “Cryogenic optical lattice clocks,” Nat. Photonics 9, 185–189 (2015).
[Crossref]

2014 (7)

D. Nicolodi, B. Argence, W. Zhang, R. Le Targat, G. Santarelli, and Y. Le Coq, “Spectral purity transfer between optical wavelengths at the 10−18 level,” Nat. Photonics 8, 219–223 (2014).
[Crossref]

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506, 71–75 (2014).
[Crossref]

N. Huntemann, B. Lipphardt, C. Tamm, V. Gerginov, S. Weyers, and E. Peik, “Improved limit on a temporal variation of mp/me from comparisons of Yb+ and Cs atomic clocks,” Phys. Rev. Lett. 113, 210802 (2014).
[Crossref]

R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
[Crossref]

A. Derevianko and M. Pospelov, “Hunting for topological dark matter with atomic clocks,” Nat. Phys. 10, 933–936 (2014).
[Crossref]

K. Jung, J. Shin, J. Kang, S. Hunziker, C. K. Min, and J. Kim, “Frequency comb-based microwave transfer over fiber with 7 x 10−19 instability using fiber-loop optical-microwave phase detectors,” Opt. Lett. 39, 1577–1580 (2014).
[Crossref]

L. C. Sinclair, I. Coddington, W. C. Swann, G. B. Rieker, A. Hati, K. Iwakuni, and N. R. Newbury, “Operation of an optically coherent frequency comb outside the metrology lab,” Opt. Express 22, 6996–7006 (2014).
[Crossref]

2013 (5)

S. Droste, F. Ozimek, T. Udem, K. Predehl, T. W. Hansch, H. Schnatz, G. Grosche, and R. Holzwarth, “Optical-frequency transfer over a single-span 1840  km fiber link,” Phys. Rev. Lett. 111, 110801 (2013).
[Crossref]

N. Hinkley, J. A. Sherman, N. B. Phillips, M. Schioppo, N. D. Lemke, K. Beloy, M. Pizzocaro, C. W. Oates, and A. D. Ludlow, “An atomic clock with 10−18 instability,” Science 341, 1215–1218 (2013).
[Crossref]

F. R. Giorgetta, W. C. Swann, L. C. Sinclair, E. Baumann, I. Coddington, and N. R. Newbury, “Optical two-way time and frequency transfer over free space,” Nat. Photonics 7, 434–438 (2013).
[Crossref]

C. Hagemann, C. Grebing, T. Kessler, S. Falke, N. Lemke, C. Lisdat, H. Schnatz, F. Riehle, and U. Sterr, “Providing short-term stability of a 1.5-laser to optical clocks,” IEEE Trans. Instrum. Meas. 62, 1556–1562 (2013).
[Crossref]

G. D. Cole, W. Zhang, M. J. Martin, J. Ye, and M. Aspelmeyer, “Tenfold reduction of Brownian noise in high-reflectivity optical coatings,” Nat. Photonics 7, 644–650 (2013).
[Crossref]

2012 (3)

2011 (2)

N. R. Nand, J. G. Hartnett, E. N. Ivanov, and G. Santarelli, “Ultra-stable very-low phase-noise signal source for very long baseline interferometry using a cryocooled sapphire oscillator,” IEEE Trans. Microw. Theory Tech. 59, 2978–2986 (2011).
[Crossref]

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

2010 (4)

2009 (2)

2008 (3)

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

J. Kim, J. A. Cox, J. Chen, and F. X. Kartner, “Drift-free femtosecond timing synchronization of remote optical and microwave sources,” Nat. Photonics 2, 733–736 (2008).
[Crossref]

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

2007 (6)

S. T. Dawkins, J. J. McFerran, and A. N. Luiten, “Considerations on the measurement of the stability of oscillators with frequency counters,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 54, 918–925 (2007).
[Crossref]

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

S. M. Foreman, K. W. Holman, D. D. Hudson, D. J. Jones, and J. Ye, “Remote transfer of ultrastable frequency references via fiber networks,” Rev. Sci. Instrum. 78, 021101 (2007).
[Crossref]

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

2006 (2)

2005 (1)

M. Takamoto, F.-L. Hong, R. Higashi, and H. Katori, “An optical lattice clock,” Nature 435, 321–324 (2005).
[Crossref]

2004 (4)

H. S. Margolis, G. P. Barwood, G. Huang, H. A. Klein, S. N. Lea, K. Szymaniec, and P. Gill, “Hertz-level measurement of the optical clock frequency in a single 88Sr+ ion,” Science 306, 1355–1358 (2004).
[Crossref]

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

L. S. Ma, Z. Y. Bi, A. Bartels, L. Robertsson, M. Zucco, R. S. Windeler, G. Wilpers, C. Oates, L. Hollberg, and S. A. Diddams, “Optical frequency synthesis and comparison with uncertainty at the 10−19 level,” Science 303, 1843–1845 (2004).
[Crossref]

M. Zimmermann, C. Gohle, R. Holzwarth, T. Udem, and T. W. Hänsch, “Optical clockwork with an offset-free difference-frequency comb: accuracy of sum-and difference-frequency generation,” Opt. Lett. 29, 310–312 (2004).
[Crossref]

2003 (1)

2002 (2)

2001 (1)

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

1999 (1)

T. Okuno, M. Onishi, T. Kashiwada, S. Ishikawa, and M. Nishimura, “Silica-based functional fibers with enhanced nonlinearity and their applications,” IEEE J. Sel. Top. Quantum Electron. 5, 1385–1391 (1999).
[Crossref]

1997 (1)

L. E. Nelson, D. J. Jones, K. Tamura, H. A. Haus, and E. P. Ippen, “Ultrashort-pulse fiber ring lasers,” Appl. Phys. B 65, 277–294 (1997).
[Crossref]

1994 (1)

Abgrall, M.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Adhikari, R. X.

Adler, F.

Allan, D. W.

D. B. Sullivan, D. W. Allan, D. A. Howe, and F. L. Walls, Characterization of Clocks and Oscillators (National Institute of Standards and Technology Technical Note, 1990).

Araujo-Hauck, C.

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

Argence, B.

D. Nicolodi, B. Argence, W. Zhang, R. Le Targat, G. Santarelli, and Y. Le Coq, “Spectral purity transfer between optical wavelengths at the 10−18 level,” Nat. Photonics 8, 219–223 (2014).
[Crossref]

Ashby, N.

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

Aspelmeyer, M.

G. D. Cole, W. Zhang, M. J. Martin, J. Ye, and M. Aspelmeyer, “Tenfold reduction of Brownian noise in high-reflectivity optical coatings,” Nat. Photonics 7, 644–650 (2013).
[Crossref]

Barrett, M.

T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
[Crossref]

Bartels, A.

L. S. Ma, Z. Y. Bi, A. Bartels, L. Robertsson, M. Zucco, R. S. Windeler, G. Wilpers, C. Oates, L. Hollberg, and S. A. Diddams, “Optical frequency synthesis and comparison with uncertainty at the 10−19 level,” Science 303, 1843–1845 (2004).
[Crossref]

Barwood, G. P.

H. S. Margolis, G. P. Barwood, G. Huang, H. A. Klein, S. N. Lea, K. Szymaniec, and P. Gill, “Hertz-level measurement of the optical clock frequency in a single 88Sr+ ion,” Science 306, 1355–1358 (2004).
[Crossref]

Baumann, E.

F. R. Giorgetta, W. C. Swann, L. C. Sinclair, E. Baumann, I. Coddington, and N. R. Newbury, “Optical two-way time and frequency transfer over free space,” Nat. Photonics 7, 434–438 (2013).
[Crossref]

Baynes, F.

T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
[Crossref]

Beloy, K.

M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
[Crossref]

N. Hinkley, J. A. Sherman, N. B. Phillips, M. Schioppo, N. D. Lemke, K. Beloy, M. Pizzocaro, C. W. Oates, and A. D. Ludlow, “An atomic clock with 10−18 instability,” Science 341, 1215–1218 (2013).
[Crossref]

Bender, C. F.

Bergquist, J. C.

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

J. Ye, J. L. Peng, R. J. Jones, K. W. Holman, J. L. Hall, D. J. Jones, S. A. Diddams, J. Kitching, S. Bize, J. C. Bergquist, L. W. Hollberg, L. Robertsson, and L. S. Ma, “Delivery of high-stability optical and microwave frequency standards over an optical fiber network,” J. Opt. Soc. Am. B 20, 1459–1467 (2003).
[Crossref]

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

Bi, Z.

Y. Yao, Y. Jiang, H. Yu, Z. Bi, and L. Ma, “Optical frequency divider with division uncertainty at the 10−21 level,” Natl. Sci. Rev. 3, 463–469 (2016).
[Crossref]

Bi, Z. Y.

L. S. Ma, Z. Y. Bi, A. Bartels, L. Robertsson, M. Zucco, R. S. Windeler, G. Wilpers, C. Oates, L. Hollberg, and S. A. Diddams, “Optical frequency synthesis and comparison with uncertainty at the 10−19 level,” Science 303, 1843–1845 (2004).
[Crossref]

Bishof, M.

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506, 71–75 (2014).
[Crossref]

Bize, S.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

J. Ye, J. L. Peng, R. J. Jones, K. W. Holman, J. L. Hall, D. J. Jones, S. A. Diddams, J. Kitching, S. Bize, J. C. Bergquist, L. W. Hollberg, L. Robertsson, and L. S. Ma, “Delivery of high-stability optical and microwave frequency standards over an optical fiber network,” J. Opt. Soc. Am. B 20, 1459–1467 (2003).
[Crossref]

Bloom, B.

T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
[Crossref]

Bloom, B. J.

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506, 71–75 (2014).
[Crossref]

Bongs, K.

R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
[Crossref]

Botzer, B.

Boudot, R.

Bourgeois, P. Y.

Briles, T. C.

Bromley, S. L.

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506, 71–75 (2014).
[Crossref]

Brown, R.

M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
[Crossref]

Brusch, A.

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

Campbell, S.

T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
[Crossref]

Campbell, S. L.

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506, 71–75 (2014).
[Crossref]

Chen, J.

J. Kim, J. A. Cox, J. Chen, and F. X. Kartner, “Drift-free femtosecond timing synchronization of remote optical and microwave sources,” Nat. Photonics 2, 733–736 (2008).
[Crossref]

Chen, L.

T. Kessler, C. Hagemann, C. Grebing, T. Legero, U. Sterr, F. Riehle, M. J. Martin, L. Chen, and J. Ye, “A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity,” Nat. Photonics 6, 687–692 (2012).
[Crossref]

Chou, C. W.

C. W. Chou, D. B. Hume, T. Rosenband, and D. J. Wineland, “Optical clocks and relativity,” Science 329, 1630–1633 (2010).
[Crossref]

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

Clairon, A.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Cliche, J. F.

J. F. Cliche, B. Shillue, C. Latrasse, M. Tetu, and L. D’Addario, “A high coherence, high stability laser for the photonic local oscillator distribution of the Atacama Large Millimeter Array,” in Ground-Based Telescopes, Parts 1 and 2, J. M. Oschmann, ed. (2004), pp. 1115–1126.

Coddington, I.

L. C. Sinclair, I. Coddington, W. C. Swann, G. B. Rieker, A. Hati, K. Iwakuni, and N. R. Newbury, “Operation of an optically coherent frequency comb outside the metrology lab,” Opt. Express 22, 6996–7006 (2014).
[Crossref]

F. R. Giorgetta, W. C. Swann, L. C. Sinclair, E. Baumann, I. Coddington, and N. R. Newbury, “Optical two-way time and frequency transfer over free space,” Nat. Photonics 7, 434–438 (2013).
[Crossref]

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

Cole, G. D.

G. D. Cole, W. Zhang, M. J. Martin, J. Ye, and M. Aspelmeyer, “Tenfold reduction of Brownian noise in high-reflectivity optical coatings,” Nat. Photonics 7, 644–650 (2013).
[Crossref]

Coq, Y. L.

Cossel, K. C.

Cox, J. A.

J. Kim, J. A. Cox, J. Chen, and F. X. Kartner, “Drift-free femtosecond timing synchronization of remote optical and microwave sources,” Nat. Photonics 2, 733–736 (2008).
[Crossref]

Cundiff, S. T.

Curtis, E. A.

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

D’Addario, L.

J. F. Cliche, B. Shillue, C. Latrasse, M. Tetu, and L. D’Addario, “A high coherence, high stability laser for the photonic local oscillator distribution of the Atacama Large Millimeter Array,” in Ground-Based Telescopes, Parts 1 and 2, J. M. Oschmann, ed. (2004), pp. 1115–1126.

D’Odorico, S.

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

Daimon, Y.

Das, M.

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, “Cryogenic optical lattice clocks,” Nat. Photonics 9, 185–189 (2015).
[Crossref]

Dawkins, S. T.

S. T. Dawkins, J. J. McFerran, and A. N. Luiten, “Considerations on the measurement of the stability of oscillators with frequency counters,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 54, 918–925 (2007).
[Crossref]

Delaney, M. J.

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

Delany, M. J.

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

Derevianko, A.

A. Derevianko and M. Pospelov, “Hunting for topological dark matter with atomic clocks,” Nat. Phys. 10, 933–936 (2014).
[Crossref]

Deutsch, C.

Diddams, S. A.

G. G. Ycas, F. Quinlan, S. A. Diddams, S. Osterman, S. Mahadevan, S. Redman, R. Terrien, L. Ramsey, C. F. Bender, B. Botzer, and S. Sigurdsson, “Demonstration of on-sky calibration of astronomical spectra using a 25  GHz near-IR laser frequency comb,” Opt. Express 20, 6631–6643 (2012).
[Crossref]

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

S. A. Diddams, “The evolving optical frequency comb,” J. Opt. Soc. Am. B 27, B51–B62 (2010).
[Crossref]

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

L. S. Ma, Z. Y. Bi, A. Bartels, L. Robertsson, M. Zucco, R. S. Windeler, G. Wilpers, C. Oates, L. Hollberg, and S. A. Diddams, “Optical frequency synthesis and comparison with uncertainty at the 10−19 level,” Science 303, 1843–1845 (2004).
[Crossref]

J. Ye, J. L. Peng, R. J. Jones, K. W. Holman, J. L. Hall, D. J. Jones, S. A. Diddams, J. Kitching, S. Bize, J. C. Bergquist, L. W. Hollberg, L. Robertsson, and L. S. Ma, “Delivery of high-stability optical and microwave frequency standards over an optical fiber network,” J. Opt. Soc. Am. B 20, 1459–1467 (2003).
[Crossref]

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

Dinkelaker, A.

Dos Santos, F. P.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Droste, S.

S. Droste, F. Ozimek, T. Udem, K. Predehl, T. W. Hansch, H. Schnatz, G. Grosche, and R. Holzwarth, “Optical-frequency transfer over a single-span 1840  km fiber link,” Phys. Rev. Lett. 111, 110801 (2013).
[Crossref]

Drullinger, R. E.

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

Falke, S.

C. Hagemann, C. Grebing, T. Kessler, S. Falke, N. Lemke, C. Lisdat, H. Schnatz, F. Riehle, and U. Sterr, “Providing short-term stability of a 1.5-laser to optical clocks,” IEEE Trans. Instrum. Meas. 62, 1556–1562 (2013).
[Crossref]

Fasano, R.

M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
[Crossref]

Feder, K. S.

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

Fermann, M.

N. Ohmae, N. Kuse, M. Fermann, and H. Katori, “All-polarization-maintaining, single-port Er:fiber comb for high-stability comparison of optical lattice clocks,” Appl. Phys. Express 10, 062503 (2017).
[Crossref]

N. Kuse, J. Jiang, C.-C. Lee, T. Schibli, and M. Fermann, “All polarization-maintaining Er fiber-based optical frequency combs with nonlinear amplifying loop mirror,” Opt. Express 24, 3095–3102 (2016).
[Crossref]

Fischer, M.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Foltynowicz, A.

Foreman, S. M.

M. J. Martin, S. M. Foreman, T. Schibli, and J. Ye, “Testing ultrafast mode-locking at microhertz relative optical linewidth,” Opt. Express 17, 558–568 (2009).
[Crossref]

S. M. Foreman, K. W. Holman, D. D. Hudson, D. J. Jones, and J. Ye, “Remote transfer of ultrastable frequency references via fiber networks,” Rev. Sci. Instrum. 78, 021101 (2007).
[Crossref]

Fortier, T.

T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
[Crossref]

Fortier, T. M.

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

T. M. Fortier, J. Ye, S. T. Cundiff, and R. S. Windeler, “Nonlinear phase noise generated in air–silica microstructure fiber and its effect on carrier–envelope phase,” Opt. Lett. 27, 445–447 (2002).
[Crossref]

Gerginov, V.

N. Huntemann, B. Lipphardt, C. Tamm, V. Gerginov, S. Weyers, and E. Peik, “Improved limit on a temporal variation of mp/me from comparisons of Yb+ and Cs atomic clocks,” Phys. Rev. Lett. 113, 210802 (2014).
[Crossref]

Gill, P.

L. Johnson, P. Gill, and H. Margolis, “Evaluating the performance of the NPL femtosecond frequency combs: agreement at the 10−21 level,” Metrologia 52, 62–71 (2015).
[Crossref]

R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
[Crossref]

H. S. Margolis, G. P. Barwood, G. Huang, H. A. Klein, S. N. Lea, K. Szymaniec, and P. Gill, “Hertz-level measurement of the optical clock frequency in a single 88Sr+ ion,” Science 306, 1355–1358 (2004).
[Crossref]

Giorgetta, F. R.

F. R. Giorgetta, W. C. Swann, L. C. Sinclair, E. Baumann, I. Coddington, and N. R. Newbury, “Optical two-way time and frequency transfer over free space,” Nat. Photonics 7, 434–438 (2013).
[Crossref]

Giunta, M.

Godun, R. M.

R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
[Crossref]

Gohle, C.

Grebing, C.

C. Hagemann, C. Grebing, T. Kessler, S. Falke, N. Lemke, C. Lisdat, H. Schnatz, F. Riehle, and U. Sterr, “Providing short-term stability of a 1.5-laser to optical clocks,” IEEE Trans. Instrum. Meas. 62, 1556–1562 (2013).
[Crossref]

T. Kessler, C. Hagemann, C. Grebing, T. Legero, U. Sterr, F. Riehle, M. J. Martin, L. Chen, and J. Ye, “A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity,” Nat. Photonics 6, 687–692 (2012).
[Crossref]

D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).

Grosche, G.

S. Droste, F. Ozimek, T. Udem, K. Predehl, T. W. Hansch, H. Schnatz, G. Grosche, and R. Holzwarth, “Optical-frequency transfer over a single-span 1840  km fiber link,” Phys. Rev. Lett. 111, 110801 (2013).
[Crossref]

Grunert, J.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Haas, M.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Häfner, S.

D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).

Hagemann, C.

C. Hagemann, C. Grebing, T. Kessler, S. Falke, N. Lemke, C. Lisdat, H. Schnatz, F. Riehle, and U. Sterr, “Providing short-term stability of a 1.5-laser to optical clocks,” IEEE Trans. Instrum. Meas. 62, 1556–1562 (2013).
[Crossref]

T. Kessler, C. Hagemann, C. Grebing, T. Legero, U. Sterr, F. Riehle, M. J. Martin, L. Chen, and J. Ye, “A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity,” Nat. Photonics 6, 687–692 (2012).
[Crossref]

Hall, J. L.

Hansch, T. W.

S. Droste, F. Ozimek, T. Udem, K. Predehl, T. W. Hansch, H. Schnatz, G. Grosche, and R. Holzwarth, “Optical-frequency transfer over a single-span 1840  km fiber link,” Phys. Rev. Lett. 111, 110801 (2013).
[Crossref]

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Hänsch, T. W.

Hartl, I.

Hartnett, J. G.

N. R. Nand, J. G. Hartnett, E. N. Ivanov, and G. Santarelli, “Ultra-stable very-low phase-noise signal source for very long baseline interferometry using a cryocooled sapphire oscillator,” IEEE Trans. Microw. Theory Tech. 59, 2978–2986 (2011).
[Crossref]

Hati, A.

T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
[Crossref]

L. C. Sinclair, I. Coddington, W. C. Swann, G. B. Rieker, A. Hati, K. Iwakuni, and N. R. Newbury, “Operation of an optically coherent frequency comb outside the metrology lab,” Opt. Express 22, 6996–7006 (2014).
[Crossref]

Haus, H. A.

L. E. Nelson, D. J. Jones, K. Tamura, H. A. Haus, and E. P. Ippen, “Ultrashort-pulse fiber ring lasers,” Appl. Phys. B 65, 277–294 (1997).
[Crossref]

Heavner, T. P.

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

Higashi, R.

M. Takamoto, F.-L. Hong, R. Higashi, and H. Katori, “An optical lattice clock,” Nature 435, 321–324 (2005).
[Crossref]

Hinkley, N.

M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
[Crossref]

T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
[Crossref]

N. Hinkley, J. A. Sherman, N. B. Phillips, M. Schioppo, N. D. Lemke, K. Beloy, M. Pizzocaro, C. W. Oates, and A. D. Ludlow, “An atomic clock with 10−18 instability,” Science 341, 1215–1218 (2013).
[Crossref]

Hirano, M.

Hollberg, L.

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

L. S. Ma, Z. Y. Bi, A. Bartels, L. Robertsson, M. Zucco, R. S. Windeler, G. Wilpers, C. Oates, L. Hollberg, and S. A. Diddams, “Optical frequency synthesis and comparison with uncertainty at the 10−19 level,” Science 303, 1843–1845 (2004).
[Crossref]

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

Hollberg, L. W.

Holman, K. W.

Holzwarth, R.

S. Droste, F. Ozimek, T. Udem, K. Predehl, T. W. Hansch, H. Schnatz, G. Grosche, and R. Holzwarth, “Optical-frequency transfer over a single-span 1840  km fiber link,” Phys. Rev. Lett. 111, 110801 (2013).
[Crossref]

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

M. Zimmermann, C. Gohle, R. Holzwarth, T. Udem, and T. W. Hänsch, “Optical clockwork with an offset-free difference-frequency comb: accuracy of sum-and difference-frequency generation,” Opt. Lett. 29, 310–312 (2004).
[Crossref]

Hong, F. L.

Hong, F.-L.

M. Takamoto, F.-L. Hong, R. Higashi, and H. Katori, “An optical lattice clock,” Nature 435, 321–324 (2005).
[Crossref]

Hosaka, K.

Howe, D. A.

D. B. Sullivan, D. W. Allan, D. A. Howe, and F. L. Walls, Characterization of Clocks and Oscillators (National Institute of Standards and Technology Technical Note, 1990).

Huang, G.

H. S. Margolis, G. P. Barwood, G. Huang, H. A. Klein, S. N. Lea, K. Szymaniec, and P. Gill, “Hertz-level measurement of the optical clock frequency in a single 88Sr+ ion,” Science 306, 1355–1358 (2004).
[Crossref]

Hudson, D. D.

S. M. Foreman, K. W. Holman, D. D. Hudson, D. J. Jones, and J. Ye, “Remote transfer of ultrastable frequency references via fiber networks,” Rev. Sci. Instrum. 78, 021101 (2007).
[Crossref]

Hume, D. B.

C. W. Chou, D. B. Hume, T. Rosenband, and D. J. Wineland, “Optical clocks and relativity,” Science 329, 1630–1633 (2010).
[Crossref]

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

Huntemann, N.

N. Huntemann, B. Lipphardt, C. Tamm, V. Gerginov, S. Weyers, and E. Peik, “Improved limit on a temporal variation of mp/me from comparisons of Yb+ and Cs atomic clocks,” Phys. Rev. Lett. 113, 210802 (2014).
[Crossref]

Hunziker, S.

Hutson, R.

T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
[Crossref]

Inaba, H.

Ippen, E. P.

L. E. Nelson, D. J. Jones, K. Tamura, H. A. Haus, and E. P. Ippen, “Ultrashort-pulse fiber ring lasers,” Appl. Phys. B 65, 277–294 (1997).
[Crossref]

Ishibashi, T.

T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
[Crossref]

Ishikawa, S.

T. Okuno, M. Onishi, T. Kashiwada, S. Ishikawa, and M. Nishimura, “Silica-based functional fibers with enhanced nonlinearity and their applications,” IEEE J. Sel. Top. Quantum Electron. 5, 1385–1391 (1999).
[Crossref]

Itano, W. M.

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

Ivanov, E. N.

N. R. Nand, J. G. Hartnett, E. N. Ivanov, and G. Santarelli, “Ultra-stable very-low phase-noise signal source for very long baseline interferometry using a cryocooled sapphire oscillator,” IEEE Trans. Microw. Theory Tech. 59, 2978–2986 (2011).
[Crossref]

Iwakuni, K.

Jefferts, S. R.

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

Jentschura, U. D.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Jiang, J.

Jiang, Y.

Y. Yao, Y. Jiang, H. Yu, Z. Bi, and L. Ma, “Optical frequency divider with division uncertainty at the 10−21 level,” Natl. Sci. Rev. 3, 463–469 (2016).
[Crossref]

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

Johnson, L.

L. Johnson, P. Gill, and H. Margolis, “Evaluating the performance of the NPL femtosecond frequency combs: agreement at the 10−21 level,” Metrologia 52, 62–71 (2015).
[Crossref]

Johnson, L. A. M.

R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
[Crossref]

Jones, D. J.

S. M. Foreman, K. W. Holman, D. D. Hudson, D. J. Jones, and J. Ye, “Remote transfer of ultrastable frequency references via fiber networks,” Rev. Sci. Instrum. 78, 021101 (2007).
[Crossref]

J. Ye, J. L. Peng, R. J. Jones, K. W. Holman, J. L. Hall, D. J. Jones, S. A. Diddams, J. Kitching, S. Bize, J. C. Bergquist, L. W. Hollberg, L. Robertsson, and L. S. Ma, “Delivery of high-stability optical and microwave frequency standards over an optical fiber network,” J. Opt. Soc. Am. B 20, 1459–1467 (2003).
[Crossref]

L. E. Nelson, D. J. Jones, K. Tamura, H. A. Haus, and E. P. Ippen, “Ultrashort-pulse fiber ring lasers,” Appl. Phys. B 65, 277–294 (1997).
[Crossref]

Jones, J. M.

R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
[Crossref]

Jones, R. J.

Jung, K.

Jungner, P.

Kang, J.

Kartner, F. X.

J. Kim, J. A. Cox, J. Chen, and F. X. Kartner, “Drift-free femtosecond timing synchronization of remote optical and microwave sources,” Nat. Photonics 2, 733–736 (2008).
[Crossref]

Kashiwada, T.

T. Okuno, M. Onishi, T. Kashiwada, S. Ishikawa, and M. Nishimura, “Silica-based functional fibers with enhanced nonlinearity and their applications,” IEEE J. Sel. Top. Quantum Electron. 5, 1385–1391 (1999).
[Crossref]

Katori, H.

N. Ohmae, N. Kuse, M. Fermann, and H. Katori, “All-polarization-maintaining, single-port Er:fiber comb for high-stability comparison of optical lattice clocks,” Appl. Phys. Express 10, 062503 (2017).
[Crossref]

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, “Cryogenic optical lattice clocks,” Nat. Photonics 9, 185–189 (2015).
[Crossref]

M. Takamoto, F.-L. Hong, R. Higashi, and H. Katori, “An optical lattice clock,” Nature 435, 321–324 (2005).
[Crossref]

Katsuyama, T.

Kawato, S.

Keitel, C. H.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Kentischer, T.

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

Kersalé, Y.

Kessler, T.

C. Hagemann, C. Grebing, T. Kessler, S. Falke, N. Lemke, C. Lisdat, H. Schnatz, F. Riehle, and U. Sterr, “Providing short-term stability of a 1.5-laser to optical clocks,” IEEE Trans. Instrum. Meas. 62, 1556–1562 (2013).
[Crossref]

T. Kessler, C. Hagemann, C. Grebing, T. Legero, U. Sterr, F. Riehle, M. J. Martin, L. Chen, and J. Ye, “A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity,” Nat. Photonics 6, 687–692 (2012).
[Crossref]

Kim, J.

K. Jung, J. Shin, J. Kang, S. Hunziker, C. K. Min, and J. Kim, “Frequency comb-based microwave transfer over fiber with 7 x 10−19 instability using fiber-loop optical-microwave phase detectors,” Opt. Lett. 39, 1577–1580 (2014).
[Crossref]

J. Kim, J. A. Cox, J. Chen, and F. X. Kartner, “Drift-free femtosecond timing synchronization of remote optical and microwave sources,” Nat. Photonics 2, 733–736 (2008).
[Crossref]

Kim, K.

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

King, S. A.

R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
[Crossref]

Kirchner, M. S.

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

Kitching, J.

Klein, H. A.

H. S. Margolis, G. P. Barwood, G. Huang, H. A. Klein, S. N. Lea, K. Szymaniec, and P. Gill, “Hertz-level measurement of the optical clock frequency in a single 88Sr+ ion,” Science 306, 1355–1358 (2004).
[Crossref]

Kobayashi, T.

Koelemeij, J. C. J.

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

Kohfeldt, A.

Kohno, T.

Kolachevsky, N.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Kolkowitz, S.

S. Kolkowitz, I. Pikovski, N. Langellier, M. D. Lukin, R. L. Walsworth, and J. Ye, “Gravitational wave detection with optical lattice atomic clocks,” Phys. Rev. D 94, 124043 (2016).
[Crossref]

Kuse, N.

N. Ohmae, N. Kuse, M. Fermann, and H. Katori, “All-polarization-maintaining, single-port Er:fiber comb for high-stability comparison of optical lattice clocks,” Appl. Phys. Express 10, 062503 (2017).
[Crossref]

N. Kuse, J. Jiang, C.-C. Lee, T. Schibli, and M. Fermann, “All polarization-maintaining Er fiber-based optical frequency combs with nonlinear amplifying loop mirror,” Opt. Express 24, 3095–3102 (2016).
[Crossref]

Langellier, N.

S. Kolkowitz, I. Pikovski, N. Langellier, M. D. Lukin, R. L. Walsworth, and J. Ye, “Gravitational wave detection with optical lattice atomic clocks,” Phys. Rev. D 94, 124043 (2016).
[Crossref]

Latrasse, C.

J. F. Cliche, B. Shillue, C. Latrasse, M. Tetu, and L. D’Addario, “A high coherence, high stability laser for the photonic local oscillator distribution of the Atacama Large Millimeter Array,” in Ground-Based Telescopes, Parts 1 and 2, J. M. Oschmann, ed. (2004), pp. 1115–1126.

Laurent, P.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Le Coq, Y.

D. Nicolodi, B. Argence, W. Zhang, R. Le Targat, G. Santarelli, and Y. Le Coq, “Spectral purity transfer between optical wavelengths at the 10−18 level,” Nat. Photonics 8, 219–223 (2014).
[Crossref]

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

Le Targat, R.

D. Nicolodi, B. Argence, W. Zhang, R. Le Targat, G. Santarelli, and Y. Le Coq, “Spectral purity transfer between optical wavelengths at the 10−18 level,” Nat. Photonics 8, 219–223 (2014).
[Crossref]

Lea, S. N.

R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
[Crossref]

H. S. Margolis, G. P. Barwood, G. Huang, H. A. Klein, S. N. Lea, K. Szymaniec, and P. Gill, “Hertz-level measurement of the optical clock frequency in a single 88Sr+ ion,” Science 306, 1355–1358 (2004).
[Crossref]

Lee, C.-C.

Lee, W. D.

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

Legero, T.

T. Kessler, C. Hagemann, C. Grebing, T. Legero, U. Sterr, F. Riehle, M. J. Martin, L. Chen, and J. Ye, “A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity,” Nat. Photonics 6, 687–692 (2012).
[Crossref]

D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).

Lemke, N.

C. Hagemann, C. Grebing, T. Kessler, S. Falke, N. Lemke, C. Lisdat, H. Schnatz, F. Riehle, and U. Sterr, “Providing short-term stability of a 1.5-laser to optical clocks,” IEEE Trans. Instrum. Meas. 62, 1556–1562 (2013).
[Crossref]

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

Lemke, N. D.

N. Hinkley, J. A. Sherman, N. B. Phillips, M. Schioppo, N. D. Lemke, K. Beloy, M. Pizzocaro, C. W. Oates, and A. D. Ludlow, “An atomic clock with 10−18 instability,” Science 341, 1215–1218 (2013).
[Crossref]

Lemonde, P.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Levi, F.

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

Lezius, M.

Lipphardt, B.

N. Huntemann, B. Lipphardt, C. Tamm, V. Gerginov, S. Weyers, and E. Peik, “Improved limit on a temporal variation of mp/me from comparisons of Yb+ and Cs atomic clocks,” Phys. Rev. Lett. 113, 210802 (2014).
[Crossref]

Lisdat, C.

C. Hagemann, C. Grebing, T. Kessler, S. Falke, N. Lemke, C. Lisdat, H. Schnatz, F. Riehle, and U. Sterr, “Providing short-term stability of a 1.5-laser to optical clocks,” IEEE Trans. Instrum. Meas. 62, 1556–1562 (2013).
[Crossref]

Lorini, L.

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

Lours, M.

Ludlow, A.

T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
[Crossref]

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

Ludlow, A. D.

N. Hinkley, J. A. Sherman, N. B. Phillips, M. Schioppo, N. D. Lemke, K. Beloy, M. Pizzocaro, C. W. Oates, and A. D. Ludlow, “An atomic clock with 10−18 instability,” Science 341, 1215–1218 (2013).
[Crossref]

Luiten, A. N.

J. Millo, R. Boudot, M. Lours, P. Y. Bourgeois, A. N. Luiten, Y. L. Coq, Y. Kersalé, and G. Santarelli, “Ultra-low-noise microwave extraction from fiber-based optical frequency comb,” Opt. Lett. 34, 3707–3709 (2009).
[Crossref]

S. T. Dawkins, J. J. McFerran, and A. N. Luiten, “Considerations on the measurement of the stability of oscillators with frequency counters,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 54, 918–925 (2007).
[Crossref]

Lukin, M. D.

S. Kolkowitz, I. Pikovski, N. Langellier, M. D. Lukin, R. L. Walsworth, and J. Ye, “Gravitational wave detection with optical lattice atomic clocks,” Phys. Rev. D 94, 124043 (2016).
[Crossref]

Ma, L.

Y. Yao, Y. Jiang, H. Yu, Z. Bi, and L. Ma, “Optical frequency divider with division uncertainty at the 10−21 level,” Natl. Sci. Rev. 3, 463–469 (2016).
[Crossref]

Ma, L. S.

Mahadevan, S.

Maksimovic, I.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Mandel, O.

Manescau, A.

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

Margolis, H.

L. Johnson, P. Gill, and H. Margolis, “Evaluating the performance of the NPL femtosecond frequency combs: agreement at the 10−21 level,” Metrologia 52, 62–71 (2015).
[Crossref]

Margolis, H. S.

R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
[Crossref]

H. S. Margolis, G. P. Barwood, G. Huang, H. A. Klein, S. N. Lea, K. Szymaniec, and P. Gill, “Hertz-level measurement of the optical clock frequency in a single 88Sr+ ion,” Science 306, 1355–1358 (2004).
[Crossref]

Marion, H.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Marti, G.

T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
[Crossref]

Martin, M. J.

G. D. Cole, W. Zhang, M. J. Martin, J. Ye, and M. Aspelmeyer, “Tenfold reduction of Brownian noise in high-reflectivity optical coatings,” Nat. Photonics 7, 644–650 (2013).
[Crossref]

T. Kessler, C. Hagemann, C. Grebing, T. Legero, U. Sterr, F. Riehle, M. J. Martin, L. Chen, and J. Ye, “A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity,” Nat. Photonics 6, 687–692 (2012).
[Crossref]

M. J. Martin, S. M. Foreman, T. Schibli, and J. Ye, “Testing ultrafast mode-locking at microhertz relative optical linewidth,” Opt. Express 17, 558–568 (2009).
[Crossref]

Maslowski, P.

Matei, D.

D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).

Matsumoto, H.

McFerran, J. J.

S. T. Dawkins, J. J. McFerran, and A. N. Luiten, “Considerations on the measurement of the stability of oscillators with frequency counters,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 54, 918–925 (2007).
[Crossref]

McGrew, W.

M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
[Crossref]

McNally, R.

T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
[Crossref]

Metcalf, A.

T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
[Crossref]

Milani, G.

M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
[Crossref]

Millo, J.

Min, C. K.

Minoshima, K.

Moll, K. D.

M. J. Thorpe, K. D. Moll, R. J. Jones, B. Safdi, and J. Ye, “Broadband cavity ringdown spectroscopy for sensitive and rapid molecular detection,” Science 311, 1595–1599 (2006).
[Crossref]

Murphy, M. T.

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

Nakajima, Y.

Nakazawa, M.

Nand, N. R.

N. R. Nand, J. G. Hartnett, E. N. Ivanov, and G. Santarelli, “Ultra-stable very-low phase-noise signal source for very long baseline interferometry using a cryocooled sapphire oscillator,” IEEE Trans. Microw. Theory Tech. 59, 2978–2986 (2011).
[Crossref]

Nelson, L. E.

L. E. Nelson, D. J. Jones, K. Tamura, H. A. Haus, and E. P. Ippen, “Ultrashort-pulse fiber ring lasers,” Appl. Phys. B 65, 277–294 (1997).
[Crossref]

Newbury, N. R.

L. C. Sinclair, I. Coddington, W. C. Swann, G. B. Rieker, A. Hati, K. Iwakuni, and N. R. Newbury, “Operation of an optically coherent frequency comb outside the metrology lab,” Opt. Express 22, 6996–7006 (2014).
[Crossref]

F. R. Giorgetta, W. C. Swann, L. C. Sinclair, E. Baumann, I. Coddington, and N. R. Newbury, “Optical two-way time and frequency transfer over free space,” Nat. Photonics 7, 434–438 (2013).
[Crossref]

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

Nicholson, J. W.

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

Nicholson, T.

T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
[Crossref]

Nicholson, T. L.

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506, 71–75 (2014).
[Crossref]

Nicolodi, D.

M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
[Crossref]

D. Nicolodi, B. Argence, W. Zhang, R. Le Targat, G. Santarelli, and Y. Le Coq, “Spectral purity transfer between optical wavelengths at the 10−18 level,” Nat. Photonics 8, 219–223 (2014).
[Crossref]

Nisbet-Jones, P. B. R.

R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
[Crossref]

Nishimura, M.

T. Okuno, M. Onishi, T. Kashiwada, S. Ishikawa, and M. Nishimura, “Silica-based functional fibers with enhanced nonlinearity and their applications,” IEEE J. Sel. Top. Quantum Electron. 5, 1385–1391 (1999).
[Crossref]

Oates, C.

L. S. Ma, Z. Y. Bi, A. Bartels, L. Robertsson, M. Zucco, R. S. Windeler, G. Wilpers, C. Oates, L. Hollberg, and S. A. Diddams, “Optical frequency synthesis and comparison with uncertainty at the 10−19 level,” Science 303, 1843–1845 (2004).
[Crossref]

Oates, C. W.

N. Hinkley, J. A. Sherman, N. B. Phillips, M. Schioppo, N. D. Lemke, K. Beloy, M. Pizzocaro, C. W. Oates, and A. D. Ludlow, “An atomic clock with 10−18 instability,” Science 341, 1215–1218 (2013).
[Crossref]

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

Ohkubo, T.

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, “Cryogenic optical lattice clocks,” Nat. Photonics 9, 185–189 (2015).
[Crossref]

Ohmae, N.

N. Ohmae, N. Kuse, M. Fermann, and H. Katori, “All-polarization-maintaining, single-port Er:fiber comb for high-stability comparison of optical lattice clocks,” Appl. Phys. Express 10, 062503 (2017).
[Crossref]

Okuno, T.

H. Inaba, Y. Daimon, F. L. Hong, A. Onae, K. Minoshima, T. R. Schibli, H. Matsumoto, M. Hirano, T. Okuno, M. Onishi, and M. Nakazawa, “Long-term measurement of optical frequencies using a simple, robust and low-noise fiber based frequency comb,” Opt. Express 14, 5223–5231 (2006).
[Crossref]

T. Okuno, M. Onishi, T. Kashiwada, S. Ishikawa, and M. Nishimura, “Silica-based functional fibers with enhanced nonlinearity and their applications,” IEEE J. Sel. Top. Quantum Electron. 5, 1385–1391 (1999).
[Crossref]

Onae, A.

Onishi, M.

H. Inaba, Y. Daimon, F. L. Hong, A. Onae, K. Minoshima, T. R. Schibli, H. Matsumoto, M. Hirano, T. Okuno, M. Onishi, and M. Nakazawa, “Long-term measurement of optical frequencies using a simple, robust and low-noise fiber based frequency comb,” Opt. Express 14, 5223–5231 (2006).
[Crossref]

T. Okuno, M. Onishi, T. Kashiwada, S. Ishikawa, and M. Nishimura, “Silica-based functional fibers with enhanced nonlinearity and their applications,” IEEE J. Sel. Top. Quantum Electron. 5, 1385–1391 (1999).
[Crossref]

Oskay, W. H.

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

Osterman, S.

Ozimek, F.

S. Droste, F. Ozimek, T. Udem, K. Predehl, T. W. Hansch, H. Schnatz, G. Grosche, and R. Holzwarth, “Optical-frequency transfer over a single-span 1840  km fiber link,” Phys. Rev. Lett. 111, 110801 (2013).
[Crossref]

Parker, T. E.

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

Pasquini, L.

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

Peik, E.

N. Huntemann, B. Lipphardt, C. Tamm, V. Gerginov, S. Weyers, and E. Peik, “Improved limit on a temporal variation of mp/me from comparisons of Yb+ and Cs atomic clocks,” Phys. Rev. Lett. 113, 210802 (2014).
[Crossref]

Peng, J. L.

Phillips, N. B.

N. Hinkley, J. A. Sherman, N. B. Phillips, M. Schioppo, N. D. Lemke, K. Beloy, M. Pizzocaro, C. W. Oates, and A. D. Ludlow, “An atomic clock with 10−18 instability,” Science 341, 1215–1218 (2013).
[Crossref]

Pikovski, I.

S. Kolkowitz, I. Pikovski, N. Langellier, M. D. Lukin, R. L. Walsworth, and J. Ye, “Gravitational wave detection with optical lattice atomic clocks,” Phys. Rev. D 94, 124043 (2016).
[Crossref]

Pizzocaro, M.

N. Hinkley, J. A. Sherman, N. B. Phillips, M. Schioppo, N. D. Lemke, K. Beloy, M. Pizzocaro, C. W. Oates, and A. D. Ludlow, “An atomic clock with 10−18 instability,” Science 341, 1215–1218 (2013).
[Crossref]

Pospelov, M.

A. Derevianko and M. Pospelov, “Hunting for topological dark matter with atomic clocks,” Nat. Phys. 10, 933–936 (2014).
[Crossref]

Predehl, K.

S. Droste, F. Ozimek, T. Udem, K. Predehl, T. W. Hansch, H. Schnatz, G. Grosche, and R. Holzwarth, “Optical-frequency transfer over a single-span 1840  km fiber link,” Phys. Rev. Lett. 111, 110801 (2013).
[Crossref]

Quinlan, F.

T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
[Crossref]

G. G. Ycas, F. Quinlan, S. A. Diddams, S. Osterman, S. Mahadevan, S. Redman, R. Terrien, L. Ramsey, C. F. Bender, B. Botzer, and S. Sigurdsson, “Demonstration of on-sky calibration of astronomical spectra using a 25  GHz near-IR laser frequency comb,” Opt. Express 20, 6631–6643 (2012).
[Crossref]

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

Quraishi, Q.

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

Ramsey, L.

Redman, S.

Riehle, F.

C. Hagemann, C. Grebing, T. Kessler, S. Falke, N. Lemke, C. Lisdat, H. Schnatz, F. Riehle, and U. Sterr, “Providing short-term stability of a 1.5-laser to optical clocks,” IEEE Trans. Instrum. Meas. 62, 1556–1562 (2013).
[Crossref]

T. Kessler, C. Hagemann, C. Grebing, T. Legero, U. Sterr, F. Riehle, M. J. Martin, L. Chen, and J. Ye, “A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity,” Nat. Photonics 6, 687–692 (2012).
[Crossref]

D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).

Rieker, G. B.

Robertsson, L.

L. S. Ma, Z. Y. Bi, A. Bartels, L. Robertsson, M. Zucco, R. S. Windeler, G. Wilpers, C. Oates, L. Hollberg, and S. A. Diddams, “Optical frequency synthesis and comparison with uncertainty at the 10−19 level,” Science 303, 1843–1845 (2004).
[Crossref]

J. Ye, J. L. Peng, R. J. Jones, K. W. Holman, J. L. Hall, D. J. Jones, S. A. Diddams, J. Kitching, S. Bize, J. C. Bergquist, L. W. Hollberg, L. Robertsson, and L. S. Ma, “Delivery of high-stability optical and microwave frequency standards over an optical fiber network,” J. Opt. Soc. Am. B 20, 1459–1467 (2003).
[Crossref]

Robinson, J.

D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).

Rolland, A.

T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
[Crossref]

Rosenband, T.

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

C. W. Chou, D. B. Hume, T. Rosenband, and D. J. Wineland, “Optical clocks and relativity,” Science 329, 1630–1633 (2010).
[Crossref]

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

Safdi, B.

M. J. Thorpe, K. D. Moll, R. J. Jones, B. Safdi, and J. Ye, “Broadband cavity ringdown spectroscopy for sensitive and rapid molecular detection,” Science 311, 1595–1599 (2006).
[Crossref]

Safronova, M.

T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
[Crossref]

Salomon, C.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Santarelli, G.

D. Nicolodi, B. Argence, W. Zhang, R. Le Targat, G. Santarelli, and Y. Le Coq, “Spectral purity transfer between optical wavelengths at the 10−18 level,” Nat. Photonics 8, 219–223 (2014).
[Crossref]

N. R. Nand, J. G. Hartnett, E. N. Ivanov, and G. Santarelli, “Ultra-stable very-low phase-noise signal source for very long baseline interferometry using a cryocooled sapphire oscillator,” IEEE Trans. Microw. Theory Tech. 59, 2978–2986 (2011).
[Crossref]

J. Millo, R. Boudot, M. Lours, P. Y. Bourgeois, A. N. Luiten, Y. L. Coq, Y. Kersalé, and G. Santarelli, “Ultra-low-noise microwave extraction from fiber-based optical frequency comb,” Opt. Lett. 34, 3707–3709 (2009).
[Crossref]

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

Schibli, T.

Schibli, T. R.

Schiemangk, M.

Schioppo, M.

M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
[Crossref]

N. Hinkley, J. A. Sherman, N. B. Phillips, M. Schioppo, N. D. Lemke, K. Beloy, M. Pizzocaro, C. W. Oates, and A. D. Ludlow, “An atomic clock with 10−18 instability,” Science 341, 1215–1218 (2013).
[Crossref]

Schkolnik, V.

Schmidt, P. O.

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

Schmidt, W.

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

Schnatz, H.

C. Hagemann, C. Grebing, T. Kessler, S. Falke, N. Lemke, C. Lisdat, H. Schnatz, F. Riehle, and U. Sterr, “Providing short-term stability of a 1.5-laser to optical clocks,” IEEE Trans. Instrum. Meas. 62, 1556–1562 (2013).
[Crossref]

S. Droste, F. Ozimek, T. Udem, K. Predehl, T. W. Hansch, H. Schnatz, G. Grosche, and R. Holzwarth, “Optical-frequency transfer over a single-span 1840  km fiber link,” Phys. Rev. Lett. 111, 110801 (2013).
[Crossref]

J. Stenger, H. Schnatz, C. Tamm, and H. R. Telle, “Ultraprecise measurement of optical frequency ratios,” Phys. Rev. Lett. 88, 073601 (2002).
[Crossref]

Sherman, J.

M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
[Crossref]

Sherman, J. A.

N. Hinkley, J. A. Sherman, N. B. Phillips, M. Schioppo, N. D. Lemke, K. Beloy, M. Pizzocaro, C. W. Oates, and A. D. Ludlow, “An atomic clock with 10−18 instability,” Science 341, 1215–1218 (2013).
[Crossref]

Shillue, B.

J. F. Cliche, B. Shillue, C. Latrasse, M. Tetu, and L. D’Addario, “A high coherence, high stability laser for the photonic local oscillator distribution of the Atacama Large Millimeter Array,” in Ground-Based Telescopes, Parts 1 and 2, J. M. Oschmann, ed. (2004), pp. 1115–1126.

Shimizu, M.

T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
[Crossref]

Shin, J.

Shirley, J.

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

Sigurdsson, S.

Sinclair, L. C.

L. C. Sinclair, I. Coddington, W. C. Swann, G. B. Rieker, A. Hati, K. Iwakuni, and N. R. Newbury, “Operation of an optically coherent frequency comb outside the metrology lab,” Opt. Express 22, 6996–7006 (2014).
[Crossref]

F. R. Giorgetta, W. C. Swann, L. C. Sinclair, E. Baumann, I. Coddington, and N. R. Newbury, “Optical two-way time and frequency transfer over free space,” Nat. Photonics 7, 434–438 (2013).
[Crossref]

Sonderhouse, L.

D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).

Stalnaker, J. E.

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

Steinmetz, T.

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

Stenger, J.

J. Stenger, H. Schnatz, C. Tamm, and H. R. Telle, “Ultraprecise measurement of optical frequency ratios,” Phys. Rev. Lett. 88, 073601 (2002).
[Crossref]

Sterr, U.

C. Hagemann, C. Grebing, T. Kessler, S. Falke, N. Lemke, C. Lisdat, H. Schnatz, F. Riehle, and U. Sterr, “Providing short-term stability of a 1.5-laser to optical clocks,” IEEE Trans. Instrum. Meas. 62, 1556–1562 (2013).
[Crossref]

T. Kessler, C. Hagemann, C. Grebing, T. Legero, U. Sterr, F. Riehle, M. J. Martin, L. Chen, and J. Ye, “A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity,” Nat. Photonics 6, 687–692 (2012).
[Crossref]

D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).

Strouse, G.

T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
[Crossref]

Sullivan, D. B.

D. B. Sullivan, D. W. Allan, D. A. Howe, and F. L. Walls, Characterization of Clocks and Oscillators (National Institute of Standards and Technology Technical Note, 1990).

Swann, W. C.

L. C. Sinclair, I. Coddington, W. C. Swann, G. B. Rieker, A. Hati, K. Iwakuni, and N. R. Newbury, “Operation of an optically coherent frequency comb outside the metrology lab,” Opt. Express 22, 6996–7006 (2014).
[Crossref]

F. R. Giorgetta, W. C. Swann, L. C. Sinclair, E. Baumann, I. Coddington, and N. R. Newbury, “Optical two-way time and frequency transfer over free space,” Nat. Photonics 7, 434–438 (2013).
[Crossref]

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

Szymaniec, K.

R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
[Crossref]

H. S. Margolis, G. P. Barwood, G. Huang, H. A. Klein, S. N. Lea, K. Szymaniec, and P. Gill, “Hertz-level measurement of the optical clock frequency in a single 88Sr+ ion,” Science 306, 1355–1358 (2004).
[Crossref]

Takamoto, M.

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, “Cryogenic optical lattice clocks,” Nat. Photonics 9, 185–189 (2015).
[Crossref]

M. Takamoto, F.-L. Hong, R. Higashi, and H. Katori, “An optical lattice clock,” Nature 435, 321–324 (2005).
[Crossref]

Tamm, C.

N. Huntemann, B. Lipphardt, C. Tamm, V. Gerginov, S. Weyers, and E. Peik, “Improved limit on a temporal variation of mp/me from comparisons of Yb+ and Cs atomic clocks,” Phys. Rev. Lett. 113, 210802 (2014).
[Crossref]

J. Stenger, H. Schnatz, C. Tamm, and H. R. Telle, “Ultraprecise measurement of optical frequency ratios,” Phys. Rev. Lett. 88, 073601 (2002).
[Crossref]

Tamura, K.

L. E. Nelson, D. J. Jones, K. Tamura, H. A. Haus, and E. P. Ippen, “Ultrashort-pulse fiber ring lasers,” Appl. Phys. B 65, 277–294 (1997).
[Crossref]

Taylor, J.

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

Telle, H. R.

J. Stenger, H. Schnatz, C. Tamm, and H. R. Telle, “Ultraprecise measurement of optical frequency ratios,” Phys. Rev. Lett. 88, 073601 (2002).
[Crossref]

Terrien, R.

Tetu, M.

J. F. Cliche, B. Shillue, C. Latrasse, M. Tetu, and L. D’Addario, “A high coherence, high stability laser for the photonic local oscillator distribution of the Atacama Large Millimeter Array,” in Ground-Based Telescopes, Parts 1 and 2, J. M. Oschmann, ed. (2004), pp. 1115–1126.

Thaller, A.

Thorpe, M. J.

M. J. Thorpe, K. D. Moll, R. J. Jones, B. Safdi, and J. Ye, “Broadband cavity ringdown spectroscopy for sensitive and rapid molecular detection,” Science 311, 1595–1599 (2006).
[Crossref]

Udem, T.

S. Droste, F. Ozimek, T. Udem, K. Predehl, T. W. Hansch, H. Schnatz, G. Grosche, and R. Holzwarth, “Optical-frequency transfer over a single-span 1840  km fiber link,” Phys. Rev. Lett. 111, 110801 (2013).
[Crossref]

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

M. Zimmermann, C. Gohle, R. Holzwarth, T. Udem, and T. W. Hänsch, “Optical clockwork with an offset-free difference-frequency comb: accuracy of sum-and difference-frequency generation,” Opt. Lett. 29, 310–312 (2004).
[Crossref]

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

Ushijima, I.

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, “Cryogenic optical lattice clocks,” Nat. Photonics 9, 185–189 (2015).
[Crossref]

Vogel, K. R.

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

Walls, F. L.

D. B. Sullivan, D. W. Allan, D. A. Howe, and F. L. Walls, Characterization of Clocks and Oscillators (National Institute of Standards and Technology Technical Note, 1990).

Walsworth, R. L.

S. Kolkowitz, I. Pikovski, N. Langellier, M. D. Lukin, R. L. Walsworth, and J. Ye, “Gravitational wave detection with optical lattice atomic clocks,” Phys. Rev. D 94, 124043 (2016).
[Crossref]

Westbrook, P. S.

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

Weyers, S.

N. Huntemann, B. Lipphardt, C. Tamm, V. Gerginov, S. Weyers, and E. Peik, “Improved limit on a temporal variation of mp/me from comparisons of Yb+ and Cs atomic clocks,” Phys. Rev. Lett. 113, 210802 (2014).
[Crossref]

Weyrich, R.

D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).

Wilken, T.

M. Lezius, T. Wilken, C. Deutsch, M. Giunta, O. Mandel, A. Thaller, V. Schkolnik, M. Schiemangk, A. Dinkelaker, and A. Kohfeldt, “Space-borne frequency comb metrology,” Optica 3, 1381–1387 (2016).
[Crossref]

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

Williams, J. R.

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506, 71–75 (2014).
[Crossref]

Wilpers, G.

L. S. Ma, Z. Y. Bi, A. Bartels, L. Robertsson, M. Zucco, R. S. Windeler, G. Wilpers, C. Oates, L. Hollberg, and S. A. Diddams, “Optical frequency synthesis and comparison with uncertainty at the 10−19 level,” Science 303, 1843–1845 (2004).
[Crossref]

Windeler, R. S.

L. S. Ma, Z. Y. Bi, A. Bartels, L. Robertsson, M. Zucco, R. S. Windeler, G. Wilpers, C. Oates, L. Hollberg, and S. A. Diddams, “Optical frequency synthesis and comparison with uncertainty at the 10−19 level,” Science 303, 1843–1845 (2004).
[Crossref]

T. M. Fortier, J. Ye, S. T. Cundiff, and R. S. Windeler, “Nonlinear phase noise generated in air–silica microstructure fiber and its effect on carrier–envelope phase,” Opt. Lett. 27, 445–447 (2002).
[Crossref]

Wineland, D. J.

C. W. Chou, D. B. Hume, T. Rosenband, and D. J. Wineland, “Optical clocks and relativity,” Science 329, 1630–1633 (2010).
[Crossref]

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

Yao, Y.

Y. Yao, Y. Jiang, H. Yu, Z. Bi, and L. Ma, “Optical frequency divider with division uncertainty at the 10−21 level,” Natl. Sci. Rev. 3, 463–469 (2016).
[Crossref]

Yasuda, M.

Ycas, G. G.

Ye, J.

S. Kolkowitz, I. Pikovski, N. Langellier, M. D. Lukin, R. L. Walsworth, and J. Ye, “Gravitational wave detection with optical lattice atomic clocks,” Phys. Rev. D 94, 124043 (2016).
[Crossref]

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506, 71–75 (2014).
[Crossref]

G. D. Cole, W. Zhang, M. J. Martin, J. Ye, and M. Aspelmeyer, “Tenfold reduction of Brownian noise in high-reflectivity optical coatings,” Nat. Photonics 7, 644–650 (2013).
[Crossref]

T. Kessler, C. Hagemann, C. Grebing, T. Legero, U. Sterr, F. Riehle, M. J. Martin, L. Chen, and J. Ye, “A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity,” Nat. Photonics 6, 687–692 (2012).
[Crossref]

F. Adler, P. Masłowski, A. Foltynowicz, K. C. Cossel, T. C. Briles, I. Hartl, and J. Ye, “Mid-infrared Fourier transform spectroscopy with a broadband frequency comb,” Opt. Express 18, 21861–21872 (2010).
[Crossref]

M. J. Martin, S. M. Foreman, T. Schibli, and J. Ye, “Testing ultrafast mode-locking at microhertz relative optical linewidth,” Opt. Express 17, 558–568 (2009).
[Crossref]

S. M. Foreman, K. W. Holman, D. D. Hudson, D. J. Jones, and J. Ye, “Remote transfer of ultrastable frequency references via fiber networks,” Rev. Sci. Instrum. 78, 021101 (2007).
[Crossref]

M. J. Thorpe, K. D. Moll, R. J. Jones, B. Safdi, and J. Ye, “Broadband cavity ringdown spectroscopy for sensitive and rapid molecular detection,” Science 311, 1595–1599 (2006).
[Crossref]

J. Ye, J. L. Peng, R. J. Jones, K. W. Holman, J. L. Hall, D. J. Jones, S. A. Diddams, J. Kitching, S. Bize, J. C. Bergquist, L. W. Hollberg, L. Robertsson, and L. S. Ma, “Delivery of high-stability optical and microwave frequency standards over an optical fiber network,” J. Opt. Soc. Am. B 20, 1459–1467 (2003).
[Crossref]

T. M. Fortier, J. Ye, S. T. Cundiff, and R. S. Windeler, “Nonlinear phase noise generated in air–silica microstructure fiber and its effect on carrier–envelope phase,” Opt. Lett. 27, 445–447 (2002).
[Crossref]

L. S. Ma, P. Jungner, J. Ye, and J. L. Hall, “Delivering the same optical frequency at two places: accurate cancellation of phase noise introduced by an optical fiber or other time-varying path,” Opt. Lett. 19, 1777–1779 (1994).
[Crossref]

D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).

Yeaton-Massey, D.

Yoon, T.

M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
[Crossref]

Yu, H.

Y. Yao, Y. Jiang, H. Yu, Z. Bi, and L. Ma, “Optical frequency divider with division uncertainty at the 10−21 level,” Natl. Sci. Rev. 3, 463–469 (2016).
[Crossref]

Zhang, W.

T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
[Crossref]

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506, 71–75 (2014).
[Crossref]

D. Nicolodi, B. Argence, W. Zhang, R. Le Targat, G. Santarelli, and Y. Le Coq, “Spectral purity transfer between optical wavelengths at the 10−18 level,” Nat. Photonics 8, 219–223 (2014).
[Crossref]

G. D. Cole, W. Zhang, M. J. Martin, J. Ye, and M. Aspelmeyer, “Tenfold reduction of Brownian noise in high-reflectivity optical coatings,” Nat. Photonics 7, 644–650 (2013).
[Crossref]

D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).

Zhang, X.

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506, 71–75 (2014).
[Crossref]

Zimmermann, M.

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

M. Zimmermann, C. Gohle, R. Holzwarth, T. Udem, and T. W. Hänsch, “Optical clockwork with an offset-free difference-frequency comb: accuracy of sum-and difference-frequency generation,” Opt. Lett. 29, 310–312 (2004).
[Crossref]

Zucco, M.

L. S. Ma, Z. Y. Bi, A. Bartels, L. Robertsson, M. Zucco, R. S. Windeler, G. Wilpers, C. Oates, L. Hollberg, and S. A. Diddams, “Optical frequency synthesis and comparison with uncertainty at the 10−19 level,” Science 303, 1843–1845 (2004).
[Crossref]

Appl. Phys. B (2)

J. E. Stalnaker, S. A. Diddams, T. M. Fortier, K. Kim, L. Hollberg, J. C. Bergquist, W. M. Itano, M. J. Delany, L. Lorini, W. H. Oskay, T. P. Heavner, S. R. Jefferts, F. Levi, T. E. Parker, and J. Shirley, “Optical-to-microwave frequency comparison with fractional uncertainty of 10−15,” Appl. Phys. B 89, 167–176 (2007).
[Crossref]

L. E. Nelson, D. J. Jones, K. Tamura, H. A. Haus, and E. P. Ippen, “Ultrashort-pulse fiber ring lasers,” Appl. Phys. B 65, 277–294 (1997).
[Crossref]

Appl. Phys. Express (1)

N. Ohmae, N. Kuse, M. Fermann, and H. Katori, “All-polarization-maintaining, single-port Er:fiber comb for high-stability comparison of optical lattice clocks,” Appl. Phys. Express 10, 062503 (2017).
[Crossref]

IEEE J. Sel. Top. Quantum Electron. (1)

T. Okuno, M. Onishi, T. Kashiwada, S. Ishikawa, and M. Nishimura, “Silica-based functional fibers with enhanced nonlinearity and their applications,” IEEE J. Sel. Top. Quantum Electron. 5, 1385–1391 (1999).
[Crossref]

IEEE Trans. Instrum. Meas. (1)

C. Hagemann, C. Grebing, T. Kessler, S. Falke, N. Lemke, C. Lisdat, H. Schnatz, F. Riehle, and U. Sterr, “Providing short-term stability of a 1.5-laser to optical clocks,” IEEE Trans. Instrum. Meas. 62, 1556–1562 (2013).
[Crossref]

IEEE Trans. Microw. Theory Tech. (1)

N. R. Nand, J. G. Hartnett, E. N. Ivanov, and G. Santarelli, “Ultra-stable very-low phase-noise signal source for very long baseline interferometry using a cryocooled sapphire oscillator,” IEEE Trans. Microw. Theory Tech. 59, 2978–2986 (2011).
[Crossref]

IEEE Trans. Ultrason. Ferroelectr. Freq. Control (1)

S. T. Dawkins, J. J. McFerran, and A. N. Luiten, “Considerations on the measurement of the stability of oscillators with frequency counters,” IEEE Trans. Ultrason. Ferroelectr. Freq. Control 54, 918–925 (2007).
[Crossref]

J. Opt. Soc. Am. B (2)

Laser Photon. Rev. (1)

T. Fortier, A. Rolland, F. Quinlan, F. Baynes, A. Metcalf, A. Hati, A. Ludlow, N. Hinkley, M. Shimizu, and T. Ishibashi, “Optically referenced broadband electronic synthesizer with 15 digits of resolution,” Laser Photon. Rev. 10, 780–790 (2016).
[Crossref]

Metrologia (1)

L. Johnson, P. Gill, and H. Margolis, “Evaluating the performance of the NPL femtosecond frequency combs: agreement at the 10−21 level,” Metrologia 52, 62–71 (2015).
[Crossref]

Nat. Commun. (1)

T. Nicholson, S. Campbell, R. Hutson, G. Marti, B. Bloom, R. McNally, W. Zhang, M. Barrett, M. Safronova, and G. Strouse, “Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty,” Nat. Commun. 6, 6896 (2015).
[Crossref]

Nat. Photonics (9)

M. Schioppo, R. Brown, W. McGrew, N. Hinkley, R. Fasano, K. Beloy, T. Yoon, G. Milani, D. Nicolodi, and J. Sherman, “Ultrastable optical clock with two cold-atom ensembles,” Nat. Photonics 11, 48–52 (2017).
[Crossref]

G. D. Cole, W. Zhang, M. J. Martin, J. Ye, and M. Aspelmeyer, “Tenfold reduction of Brownian noise in high-reflectivity optical coatings,” Nat. Photonics 7, 644–650 (2013).
[Crossref]

T. Kessler, C. Hagemann, C. Grebing, T. Legero, U. Sterr, F. Riehle, M. J. Martin, L. Chen, and J. Ye, “A sub-40-mHz-linewidth laser based on a silicon single-crystal optical cavity,” Nat. Photonics 6, 687–692 (2012).
[Crossref]

I. Coddington, W. C. Swann, L. Lorini, J. C. Bergquist, Y. Le Coq, C. W. Oates, Q. Quraishi, K. S. Feder, J. W. Nicholson, P. S. Westbrook, S. A. Diddams, and N. R. Newbury, “Coherent optical link over hundreds of metres and hundreds of terahertz with subfemtosecond timing jitter,” Nat. Photonics 1, 283–287 (2007).
[Crossref]

J. Kim, J. A. Cox, J. Chen, and F. X. Kartner, “Drift-free femtosecond timing synchronization of remote optical and microwave sources,” Nat. Photonics 2, 733–736 (2008).
[Crossref]

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, “Cryogenic optical lattice clocks,” Nat. Photonics 9, 185–189 (2015).
[Crossref]

D. Nicolodi, B. Argence, W. Zhang, R. Le Targat, G. Santarelli, and Y. Le Coq, “Spectral purity transfer between optical wavelengths at the 10−18 level,” Nat. Photonics 8, 219–223 (2014).
[Crossref]

T. M. Fortier, M. S. Kirchner, F. Quinlan, J. Taylor, J. C. Bergquist, T. Rosenband, N. Lemke, A. Ludlow, Y. Jiang, C. W. Oates, and S. A. Diddams, “Generation of ultrastable microwaves via optical frequency division,” Nat. Photonics 5, 425–429 (2011).
[Crossref]

F. R. Giorgetta, W. C. Swann, L. C. Sinclair, E. Baumann, I. Coddington, and N. R. Newbury, “Optical two-way time and frequency transfer over free space,” Nat. Photonics 7, 434–438 (2013).
[Crossref]

Nat. Phys. (1)

A. Derevianko and M. Pospelov, “Hunting for topological dark matter with atomic clocks,” Nat. Phys. 10, 933–936 (2014).
[Crossref]

Natl. Sci. Rev. (1)

Y. Yao, Y. Jiang, H. Yu, Z. Bi, and L. Ma, “Optical frequency divider with division uncertainty at the 10−21 level,” Natl. Sci. Rev. 3, 463–469 (2016).
[Crossref]

Nature (2)

M. Takamoto, F.-L. Hong, R. Higashi, and H. Katori, “An optical lattice clock,” Nature 435, 321–324 (2005).
[Crossref]

B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, “An optical lattice clock with accuracy and stability at the 10−18 level,” Nature 506, 71–75 (2014).
[Crossref]

Opt. Express (8)

H. Inaba, Y. Daimon, F. L. Hong, A. Onae, K. Minoshima, T. R. Schibli, H. Matsumoto, M. Hirano, T. Okuno, M. Onishi, and M. Nakazawa, “Long-term measurement of optical frequencies using a simple, robust and low-noise fiber based frequency comb,” Opt. Express 14, 5223–5231 (2006).
[Crossref]

M. J. Martin, S. M. Foreman, T. Schibli, and J. Ye, “Testing ultrafast mode-locking at microhertz relative optical linewidth,” Opt. Express 17, 558–568 (2009).
[Crossref]

Y. Nakajima, H. Inaba, K. Hosaka, K. Minoshima, A. Onae, M. Yasuda, T. Kohno, S. Kawato, T. Kobayashi, and T. Katsuyama, “A multi-branch, fiber-based frequency comb with millihertz-level relative linewidths using an intra-cavity electro-optic modulator,” Opt. Express 18, 1667–1676 (2010).
[Crossref]

F. Adler, P. Masłowski, A. Foltynowicz, K. C. Cossel, T. C. Briles, I. Hartl, and J. Ye, “Mid-infrared Fourier transform spectroscopy with a broadband frequency comb,” Opt. Express 18, 21861–21872 (2010).
[Crossref]

G. G. Ycas, F. Quinlan, S. A. Diddams, S. Osterman, S. Mahadevan, S. Redman, R. Terrien, L. Ramsey, C. F. Bender, B. Botzer, and S. Sigurdsson, “Demonstration of on-sky calibration of astronomical spectra using a 25  GHz near-IR laser frequency comb,” Opt. Express 20, 6631–6643 (2012).
[Crossref]

D. Yeaton-Massey and R. X. Adhikari, “A new bound on excess frequency noise in second harmonic generation in PPKTP at the 10−19 level,” Opt. Express 20, 21019–21024 (2012).
[Crossref]

L. C. Sinclair, I. Coddington, W. C. Swann, G. B. Rieker, A. Hati, K. Iwakuni, and N. R. Newbury, “Operation of an optically coherent frequency comb outside the metrology lab,” Opt. Express 22, 6996–7006 (2014).
[Crossref]

N. Kuse, J. Jiang, C.-C. Lee, T. Schibli, and M. Fermann, “All polarization-maintaining Er fiber-based optical frequency combs with nonlinear amplifying loop mirror,” Opt. Express 24, 3095–3102 (2016).
[Crossref]

Opt. Lett. (5)

Optica (1)

Phys. Rev. D (1)

S. Kolkowitz, I. Pikovski, N. Langellier, M. D. Lukin, R. L. Walsworth, and J. Ye, “Gravitational wave detection with optical lattice atomic clocks,” Phys. Rev. D 94, 124043 (2016).
[Crossref]

Phys. Rev. Lett. (7)

T. Rosenband, P. O. Schmidt, D. B. Hume, W. M. Itano, T. M. Fortier, J. E. Stalnaker, K. Kim, S. A. Diddams, J. C. J. Koelemeij, J. C. Bergquist, and D. J. Wineland, “Observation of the S-1(0)->(3)P0 clock transition in Al-27(+),” Phys. Rev. Lett. 98, 220801 (2007).
[Crossref]

S. Droste, F. Ozimek, T. Udem, K. Predehl, T. W. Hansch, H. Schnatz, G. Grosche, and R. Holzwarth, “Optical-frequency transfer over a single-span 1840  km fiber link,” Phys. Rev. Lett. 111, 110801 (2013).
[Crossref]

T. M. Fortier, N. Ashby, J. C. Bergquist, M. J. Delaney, S. A. Diddams, T. P. Heavner, L. Hollberg, W. M. Itano, S. R. Jefferts, K. Kim, F. Levi, L. Lorini, W. H. Oskay, T. E. Parker, and J. E. Stalnaker, “Precision atomic spectroscopy for improved limits on variation of the fine structure constant and local position invariance,” Phys. Rev. Lett. 98, 070801 (2007).
[Crossref]

N. Huntemann, B. Lipphardt, C. Tamm, V. Gerginov, S. Weyers, and E. Peik, “Improved limit on a temporal variation of mp/me from comparisons of Yb+ and Cs atomic clocks,” Phys. Rev. Lett. 113, 210802 (2014).
[Crossref]

M. Fischer, N. Kolachevsky, M. Zimmermann, R. Holzwarth, T. Udem, T. W. Hansch, M. Abgrall, J. Grunert, I. Maksimovic, S. Bize, H. Marion, F. P. Dos Santos, P. Lemonde, G. Santarelli, P. Laurent, A. Clairon, C. Salomon, M. Haas, U. D. Jentschura, and C. H. Keitel, “New limits on the drift of fundamental constants from laboratory measurements,” Phys. Rev. Lett. 92, 230802 (2004).
[Crossref]

R. M. Godun, P. B. R. Nisbet-Jones, J. M. Jones, S. A. King, L. A. M. Johnson, H. S. Margolis, K. Szymaniec, S. N. Lea, K. Bongs, and P. Gill, “Frequency ratio of two optical clock transitions in Yb-171(+) and constraints on the time variation of fundamental constants,” Phys. Rev. Lett. 113, 210801 (2014).
[Crossref]

J. Stenger, H. Schnatz, C. Tamm, and H. R. Telle, “Ultraprecise measurement of optical frequency ratios,” Phys. Rev. Lett. 88, 073601 (2002).
[Crossref]

Rev. Sci. Instrum. (1)

S. M. Foreman, K. W. Holman, D. D. Hudson, D. J. Jones, and J. Ye, “Remote transfer of ultrastable frequency references via fiber networks,” Rev. Sci. Instrum. 78, 021101 (2007).
[Crossref]

Science (8)

H. S. Margolis, G. P. Barwood, G. Huang, H. A. Klein, S. N. Lea, K. Szymaniec, and P. Gill, “Hertz-level measurement of the optical clock frequency in a single 88Sr+ ion,” Science 306, 1355–1358 (2004).
[Crossref]

C. W. Chou, D. B. Hume, T. Rosenband, and D. J. Wineland, “Optical clocks and relativity,” Science 329, 1630–1633 (2010).
[Crossref]

T. Rosenband, D. B. Hume, P. O. Schmidt, C. W. Chou, A. Brusch, L. Lorini, W. H. Oskay, R. E. Drullinger, T. M. Fortier, J. E. Stalnaker, S. A. Diddams, W. C. Swann, N. R. Newbury, W. M. Itano, D. J. Wineland, and J. C. Bergquist, “Frequency ratio of Al+ and Hg+ single-ion optical clocks; metrology at the 17th decimal place,” Science 319, 1808–1812 (2008).
[Crossref]

N. Hinkley, J. A. Sherman, N. B. Phillips, M. Schioppo, N. D. Lemke, K. Beloy, M. Pizzocaro, C. W. Oates, and A. D. Ludlow, “An atomic clock with 10−18 instability,” Science 341, 1215–1218 (2013).
[Crossref]

L. S. Ma, Z. Y. Bi, A. Bartels, L. Robertsson, M. Zucco, R. S. Windeler, G. Wilpers, C. Oates, L. Hollberg, and S. A. Diddams, “Optical frequency synthesis and comparison with uncertainty at the 10−19 level,” Science 303, 1843–1845 (2004).
[Crossref]

M. J. Thorpe, K. D. Moll, R. J. Jones, B. Safdi, and J. Ye, “Broadband cavity ringdown spectroscopy for sensitive and rapid molecular detection,” Science 311, 1595–1599 (2006).
[Crossref]

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hansch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, and T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008).
[Crossref]

S. A. Diddams, T. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, “An optical clock based on a single trapped Hg ion,” Science 293, 825–828 (2001).
[Crossref]

Other (3)

D. B. Sullivan, D. W. Allan, D. A. Howe, and F. L. Walls, Characterization of Clocks and Oscillators (National Institute of Standards and Technology Technical Note, 1990).

J. F. Cliche, B. Shillue, C. Latrasse, M. Tetu, and L. D’Addario, “A high coherence, high stability laser for the photonic local oscillator distribution of the Atacama Large Millimeter Array,” in Ground-Based Telescopes, Parts 1 and 2, J. M. Oschmann, ed. (2004), pp. 1115–1126.

D. Matei, T. Legero, S. Häfner, C. Grebing, R. Weyrich, W. Zhang, L. Sonderhouse, J. Robinson, J. Ye, F. Riehle, and U. Sterr, “1.5  μm lasers with sub 10 mHz linewidth,” arXiv:1702.04669 (2017).

Supplementary Material (1)

NameDescription
» Supplement 1       Supplement

Cited By

OSA participates in Crossref's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (4)

Fig. 1.
Fig. 1. (a) Block diagram highlighting the single-branch OFC architecture. (b) The optical spectrum after optical amplification and external broadening in PM highly nonlinear fiber and its overlap with the various optical frequency standards and references at the National Institute of Standards and Technology (NIST), Boulder. Colors correspond to wavelength regions highlighted in (a). (c) The optical offset frequency detected near 1070 nm in a 300 kHz resolution bandwidth. Optical heterodyne beat signals shown in a 300 kHz resolution bandwidth between the optical spectrum in Fig. 1(b) with the Al+ clock laser at 1070 nm in green, the ytterbium lattice clock laser at 1157 nm in purple, and the Ca clock laser at 657 nm in red. These signals are offset from each other by arbitrary frequencies to show the relative strengths of the signal.
Fig. 2.
Fig. 2. (a) Simplified diagram of the single-comb measurement technique. The OFC is referenced to a cw laser, and a synthesized frequency an octave away is then doubled to that of the incoming light. This doubled light is then mixed with the original cw laser to determine the performance of the device under test, namely, the OFC and PPLN crystal used for doubling. (b) The single-comb measurement technique used to characterize the instability added by the single-branch OFC to an out-of-loop optical frequency measurement. Here fbopt_in measures the in-loop optical beat signal between the reference laser and the frequency comb that is used for stabilization of the laser repetition rate. To determine the instability the OFC adds across an octave, the long wavelength end of the spectrum is doubled and heterodyned against the same reference laser used to stabilize the repetition rate. This optical beat signal, fbopt_out, measures the out-of-loop contributions of the offset frequency, f0, and the locked beat, fbopt_in, since there are optical and electronic paths that are not common to the measurement of fbopt_out. (c) Block diagram highlighting the individual noise contributions within the optical frequency comb setup to measurement of an optical frequency reference at 282 THz. The instability contributed by out-of-loop electronics is labeled with ε and noncommon path lengths with L.
Fig. 3.
Fig. 3. Itemized residual noise contributions of the single-branch OFC to an optical measurement at 282 THz measured with a 0.5 Hz noise-equivalent bandwidth. The red triangles and blue squares measure the residual noise in the f0 and fbopt_in phase-locked loops, respectively. The residual noise across the octave of an out-of-loop beat, fbopt_out, measured on the same detector (purple circles) and separate detector (black circles) as fbopt_in. The black circles show the upper limit to the noise added by two 50 cm free-space interferometers. The total contributions from the amplifier chains and the synthesizers are shown as the red solid line. The contribution of the measurement instability in counting a 10 MHz signal is shown in black. It is important to note that the counterinstability will scale linearly with the measured frequency.
Fig. 4.
Fig. 4. Residual instability and accuracy of the single-branch Er:fiber OFC (solid black lines), as well as the instability and accuracy of state-of-the-art optical cavities and optical atomic clocks (green dashed lines) [14]. The pink dashed line represents the theoretical next-generation optical atomic clocks based on a cryogenic optical cavity [33,34]. Additionally, we show the optical comparison between a Yb lattice clock laser and an Al+-ion clock laser with the single-branch OFC (green crosses).

Equations (7)

Equations on this page are rendered with MathJax. Learn more.

νN=N×frep+f0.
νopt1=N×frep+f0+fbopt1.
νopt2=MN(νopt1f0fbopt1)+f0+fbopt2.
2×νNν2N=f0.
νopt=2N×frep+f0+fbopt_in.
νopt2(N×frep+f0)+γ=fbopt_out.
fbopt_out=fbopt_inf0+γ.

Metrics