Abstract

Entanglement, describing the inseparability of a quantum multiparty system, is one of the most intriguing features of quantum mechanics. Violation of Bell inequality, for ruling out the possibility of local hidden-variable theories, is commonly used as a strong witness of quantum entanglement. In previous Bell test experiments with photonic entanglement based on two-photon coincidence measurement, the photon temporal wave packets were absorbed completely by the detectors. That is, the photon coherence time is much shorter than the detection time window. Here we demonstrate the generation of frequency-bin entangled narrowband biphotons, and for the first time, to the best of our knowledge, test the Clauser–Horne–Shimony–Holt (CHSH) Bell inequality |S|2 for their nonlocal temporal correlations with time-resolved detection. We obtain a maximum |S| value of 2.52±0.48, which violates the CHSH inequality. Our result will have applications in quantum information processing involving time-frequency entanglement.

© 2017 Optical Society of America

1. INTRODUCTION

As one of the most important features of quantum mechanics, entanglement is essential in quantum information processing, quantum computation, and quantum communication [1]. Photonic entanglement has been realized in diverse degrees of freedom, including polarization [24], position momentum [5,6], orbital angular momentum [7], and time frequency [814]. The nonlocal correlations between distant entangled photons provide a standard platform for the Bell test [1517] and confirm that quantum mechanics is incompatible with the local hidden-variable theories, which is the essence of the Einstein–Podolsky–Rosen (EPR) paradox [18]. Recently, a loophole-free test of Bell’s theorem has been demonstrated [19,20]. On the other side, violation of Bell inequality is often used as an entanglement witness.

In most previous experimental tests of Bell’s theorem with entangled photons, including these loophole-free tests [19,20], the photon wave packets were absorbed completely by the coincidence detectors. That is, the photon coherence time is much shorter than the detection time window. In these works, the photon coincidence detection is modelled as integral over the entire wave packets. Surprisingly, although time-frequency entanglement has been studied intensively [810,1214], the nonlocal correlation between the arrival times of frequency-bin entangled photons on the detectors (or the biphoton temporal correlation) has never been used for testing Bell’s theorem. In all previous experiments of the Bell test, the Bell parameter S is a function of the detectors’ local settings (such as polarizations in polarization entanglement [19,20], phases in a Franson interferometer [8]), which do not include the arrival times of the photons on the distant detectors.

The recent development of narrowband biphoton generation makes it possible to reveal the rich temporal quantum state information directly using time-resolved single-photon counters. Biphotons have been produced with a bandwidth narrower than 50 MHz with spontaneous parametric down-conversion inside a cavity [21,22], spontaneous four-wave mixing (SFWM) in a hot atomic vapor cell [23], or laser-cooled atoms [2430]. On the other hand, time-resolved measurement has been demonstrated as a powerful tool in generating pure heralded single photons [31,32] and biphoton entanglement [33].

In this article, we demonstrate the generation of frequency-bin entangled narrowband biphotons using SFWM in cold atoms for testing Bell’s theorem. For the first time, we test the Clauser–Horne–Shimony–Holt (CHSH) Bell inequality |S|2 for their nonlocal temporal correlations with time-resolved detection. We obtain a maximum |S| value of 2.52±0.48, which violates the CHSH inequality. Our result also reveals the connection between the visibility of the two-photon quantum temporal beating resulting from the frequency entanglement and the violation of the Bell inequality. Our work not only provides a new case of Bell test, but also opens a new way to study the time-frequency entanglement with time-resolved detection.

2. GENERATION OF FREQUENCY-BIN ENTANGLED NARROWBAND BIPHOTONS

Our experimental configuration of double-path SFWM and relevant atomic energy level diagram are illustrated in Fig. 1(a) and 1(b). We work with laser-cooled Rb85 atoms trapped in a two-dimensional (2D) magneto-optical trap (MOT) [34]. In the presence of counter-propagating pump (ωp) and coupling (ωc) laser beams along the longitudinal z axis of the 2D MOT, correlated Stokes (ωs) and anti-Stokes (ωas) photons are spontaneously generated in opposite directions and collected into two spatial symmetric single-mode paths (paths 1 and 2, respectively). We send the Stokes photons on path 1 through a frequency-phase shifter (FPS) (δ=2π×10MHz, Δϕs) so that the frequencies of these Stokes photons become ωs+δ and obtain a relative phase Δϕs to those on path 2. Symmetrically, we add a second FPS (δ, Δϕas) to the anti-Stokes photons on path 2. We then combine the two paths with two beam splitters (BS1 and BS2, 50%:50%). The single-mode outputs of the beam splitters are detected by single-photon counting modules (Ds± and Das±) as shown in Fig. 1(a). A detailed description of our experimental setup is presented in Supplement 1 [35]. The photon pairs from the beam-splitter outputs are frequency-bin entangled and their biphoton states can be described as

|ΨXY=12[|ωs+δ|ωas+XYei(ΔϕasΔϕs)|ωs|ωas+δ],
where XY, as a product of the signs (+, ), represents the Stoke-to-anti-Stokes combinations from the beam-splitter outputs: |ΨXY is detected by (DsX, DasY).

 

Fig. 1. Generation of frequency-bin entangled narrowband biphotons. (a) Experimental schematics of generating biphotons with double-path SFWM in cold Rb85 atoms. Backward and paired Stokes (ωs) and anti-Stokes (ωas) photons are spontaneously produced into paths 1 and 2, respectively, which are symmetric with angles of ±3° to the longitudinal axis. The Stokes photons on path 1 go through FPS (δ, Δϕs), while the anti-Stokes photons on path 2 go through FPS (δ, Δϕas). BS1 and BS2 are two beam splitters. Ds± and Das± are single-photon counting modules. (b) Rb85 atomic energy level diagram for SFWM. The atomic hyperfine levels are chosen as |1=|5S1/2,F=2, |2=|5S1/2,F=3, |3=|5P1/2,F=3, and |4=|5P3/2,F=3. The circularly polarized (σ) pump laser (780 nm) is blue-detuned by 60 MHz from the transition |1|4, whereas the coupling laser (σ+, 795 nm) is on resonance to the transition |2|3. Panels (c) and (d) show the biphoton temporal correlations on paths 1 and 2, respectively. (e) Biphoton quantum beating measured between detectors Ds+ and Das+ and its visibility with the phase setting Δϕs=3π/2 and Δϕas=π/4. The solid curves in panels (c)–(e) are obtained from the SFWM biphoton theory [35].

Download Full Size | PPT Slide | PDF

The Glauber correlation function of the biphoton state in Eq. (1) exhibits a quantum beating [35]:

GXY(2)(τ;Δϕs,Δϕas)=12[G0(2)(τ)N0]×[1+XYcos(δτ+ΔϕsΔϕas)]+N0,
where τ=tasts. G0(2)(τ) is the biphoton Glauber correlation function before the beam splitters, which is the same for both paths 1 and 2. N0 is the uncorrelated accidental coincidence rate. We then have the normalized biphoton correlation function,
gXY(2)(τ;Δϕs,Δϕas)=GXY(2)(τ;Δϕs,Δϕas)/N0=12[g0(2)(τ)1][1+XYcos(δτ+ΔϕsΔϕas)]+1,
where g0(2)(τ)=G0(2)(τ)/N0. When N0 is nonzero, the beating visibility slowly varies as a function of τ:
V(τ)=G0(2)(τ)N0G0(2)(τ)+N0=g0(2)(τ)1g0(2)(τ)+1.

In the ideal case under the limit of zero accidental coincidence counts, the visibility of cosine modulation in the quantum beat approaches 100%. Experimentally, the two-photon temporal correlation is measured as coincidence counts between the detectors:

CXY(τ;Δϕs,Δϕas)=GXY(2)(τ;Δϕs,Δϕas)ηξΔtbinT,
where η is the joint detection efficiency, ξ is the duty cycle, Δtbin is the detector time bin width, and T is the data collection time.

Figure 1(c) and 1(d) shows the biphoton correlations for paths 1 and 2, respectively, measured without the presence of the two beam splitters. They are nearly identical to each other with coherence time of about 300 ns, corresponding to the bandwidth of 1.28 MHz. With the two beam splitters presented, the correlation g++(2)(τ;3π/2,π/4) displays a quantum beating [shown in Fig. 1(e)], as predicted in Eq. (3).

3. BELL INEQUALITY OF FREQUENCY-BIN ENTANGLEMENT

As shown in Eqs. (2)–(5) and confirmed in our experiment, the two-photon coincidence counts are functions of the relative arrival time delay τ=tasts between the Stokes and anti-Stokes photons at the two distant detectors and the relative phase difference ΔϕsΔϕas. We set the photon counters Ds± distant enough from Das±, as well as the two FPSs, to make our Bell test locality-loophole-free. Meanwhile, we take the fair-sampling assumption. To test the CHSH-type Bell inequality [17], we define the measurement output as +1 for coincidence between Ds+ and Das+ (or Ds and Das), and 1 for coincidence between Ds+ and Das (or Ds and Das+). Then the Bell correlation coefficient can be obtained from

E(τ;Δϕs,Δϕas)=C+++CC+C+C+++C+C++C+.

As shown in Fig. 1(c) and 1(d), the biphoton waveforms for paths 1 and 2 are nearly identical with a likeness of 98% [35]. Therefore, the two SFWM paths are nearly symmetrical. Considering the symmetries of the two SFWM paths and the beam splitters, Eq. (6) can be reduced to

E(τ;Δϕs,Δϕas)=C++(τ;Δϕs,Δϕas)C++(τ;Δϕs,Δϕas)C++(τ;Δϕs,Δϕas)+C++(τ;Δϕs,Δϕas),
which requires only two photon detectors with Δϕs=Δϕs+π. Then the CHSH Bell parameter S can be estimated as
S(τ)=E(τ;Δϕs,Δϕas)E(τ;Δϕs,Δϕas)+E(τ;Δϕs,Δϕas)+E(τ;Δϕs,Δϕas).

Under local realism, the Bell inequality holds |S(τ)|2.

For the biphoton source described by Eqs. (1)–(5), setting Δϕs=Δϕsπ/2 and Δϕas=Δϕasπ/2, we derive [35]

S(τ)=22V(τ)cos(δτ+ΔϕsΔϕas+π4).

For frequency-bin entanglement approaching the ideal case without accidental coincidence counts, i.e., V(τ)1, our theory predicts |S|max22, which violates the CHSH Bell inequality. It is clear that S(τ) exhibits a sinusoidal oscillation pattern with 22V(τ) as the slowly varying envelope.

The measured S(τ) and Bell correlations E(τ) are shown in Fig. 2, with the phase setting Δϕs=0, Δϕas=π/4, Δϕs=π/2, and Δϕas=π/4. At τ=52ns, we have S=2.52±0.48, which violates the classical limit. The solid theoretical curve in Fig. 2(a) is predicted from Eq. (9) and agrees well with the experiment. The oscillation amplitude follows the dashed envelope plotted from ±22V(τ) well. By adjusting the phase setting, we can violate the Bell inequality |S|2 for 0<τ350ns, where the visibility satisfies V>1/2.

 

Fig. 2. CHSH Bell inequality of frequency-bin entanglement. (a) S as a function of a two-photon relative time delay of τ. The circles are experimental data. The solid curve is predicted by the theory. The dashed envelopes are plotted from ±22V(τ), where the visibility V(τ) is determined by Eq. (4). The shadow area is the classical regime where |S|2. Panels (b)–(e) show the measured Bell correlations. The phase settings are Δϕs=0, Δϕas=π/4, Δϕs=π/2, and Δϕas=π/4.

Download Full Size | PPT Slide | PDF

4. NONLOCAL PHASE CORRELATION

At a fixed relative time delay of τ, the two-photon correlation in Eq. (2) is identical to that obtained in polarization entanglement, where Δϕs and Δϕas correspond to the orientations of distant polarizers. To confirm this, in Fig. 3(a) we plot the measured quantum beating temporal correlations with different phase settings. Figure 3(b) shows the nonlocal phase correlation as a function of Δϕs at τ=252ns under two different Δϕas. Similarly to the polarization entanglement, the system has a rotation symmetry and the correlation depends only on the relative phase difference ΔϕsΔϕas. Therefore, the visibility of the nonlocal phase correlation V>1/2 is an indication of violation of the Bell inequality. The solid lines in Fig. 3(b) are the best fitting sinusoidal curves with visibilities of V1=0.86±0.09 for Δϕas=π/4 and V2=0.85±0.13 for Δϕas=π/4. These visibilities are consistent with the visibility envelope of the quantum beating V(τ=252ns)=0.78 in Fig. 1(e). We estimate the S value from S=2(V1+V2)=2.42±0.31, which violates the Bell inequality.

 

Fig. 3. Two-photon nonlocal phase correlation. (a) Measured biphoton temporal correlations with different phase settings. (b) Phase correlations at τ=252ns. The error bars are standard deviations resulting from the statistical uncertainties of coincidence counts. The solid lines are the best fitting curves, with visibilities of V1=0.86±0.09 for Δϕas=π/4 and V2=0.85±0.13 for Δϕas=π/4.

Download Full Size | PPT Slide | PDF

5. BIPHOTON TEMPORAL BEATING

The Bell inequality was derived for general local experimental apparatus settings. For the polarization entanglement, these settings are the orientations of the polarizers. For the time-frequency entanglement, one can choose the detection time as the local detector setting parameter. In this experiment, we take ts and tas as the two distant local parameters. For the frequency-bin entangled state we prepared here, quantum mechanics predicts that the two-photon temporal correlation exhibits a temporal quantum beating [Eq. (2)], which in mathematical form is similar to the polarization correlation from polarization entanglement. Figure 4(a) shows the temporal beatings of two-photon correlation at two different phase settings. To compare with that in a conventional polarization entanglement measurement, we normalize the quantum beating g++(2)(τ) to the correlation envelope g0(2)(τ) without subtracting the contribution from accidental photon coincidence counts. The normalized beating signals are plotted in Fig. 4(b). With sinusoidal curve fitting for the normalized beating over 200 ns, we obtain the visibilities to be V¯=0.77±0.04 and V¯=0.76±0.06, which clearly surpasses the 0.5 limit of a classical probability theory [2,37]. The corresponding |S| values are 2.17±0.11 and 2.16±0.17.

 

Fig. 4. Biphoton temporal beating. (a) Measured two-photon temporal correlations with different phase settings. The blue data are measured with Δϕs=3π/2, Δϕas=π/4 and the red data with Δϕs=π, Δϕas=π/4. (b) Normalized beating signals. The solid curves are the best fittings.

Download Full Size | PPT Slide | PDF

6. SUMMARY AND DISCUSSION

In summary, we generate frequency-bin entangled narrowband biphotons from SFWM in cold atoms with a double-path configuration, where the phase difference between the two spatial paths can be controlled independently and nonlocally. The two-photon correlation exhibits a temporal quantum beating between the entangled frequency modes whose phase is determined by the relative phase difference between the two paths. We have successfully tested the CHSH Bell inequality and our best result is |S|=2.52±0.48, which violates the Bell inequality |S|2. With V as the visibility of the two-photon temporal beating, the quantum theory predicts |S|max=22V, which is confirmed by the experiment. Therefore, the visibility V>1/2=71% of the two-photon temporal beating is sufficient to violate the Bell inequality. The experimental value of |S| is below 22 because the uncorrelated accidental coincidence counts from stray light and dark counts, and the randomness of photon pair generation in the spontaneous process reduce the beating visibility. We can reduce the pump laser power for lower accidental coincidence counts and thus for a higher visibility, but it will take a longer time for collecting data. The error bar of |S| is the standard deviation resulting from the statistical uncertainties of coincidence counts, which can also be reduced with a longer data collection time. The time-resolved single-photon detection is a powerful tool for quantum-state control, such as entanglement swapping and teleportation [14]. Our result, for the first time, tests the Bell inequality in a nonlocal temporal correlation of frequency-bin entangled narrowband biphotons with time-resolved detection, and will have applications in quantum information processing involving time-frequency entanglement [38]. Moreover, through the Bell test, we have unambiguously demonstrated the generation of frequency-bin entangled narrowband (about 1 MHz) biphotons, which can efficiently interact with stationary atomic quantum nodes in an atom–photon quantum network [39]. Because of their narrow bandwidth, these biphotons can be stored and retrieved from a quantum memory with high efficiency.

After submission of this article, we became aware that a work of creating and manipulating single photons in superposition states of two discrete frequencies was published recently [38]. Our narrowband frequency-bin entangled biphoton source in this work can be ideally implemented to produce pure heralded single photons in a two-color qubit state with a tunable phase, making use of entanglement, linear optics, and time-resolved detection [31,32,35].

Funding

Hong Kong Research Grants Council (16305615).

 

See Supplement 1 for supporting content.

REFERENCES AND NOTES

1. R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, “Quantum entanglement,” Rev. Mod. Phys. 81, 865–942 (2009). [CrossRef]  

2. Z. Y. Ou and L. Mandel, “Violation of Bell’s inequality and classical probability in a two-photon correlation experiment,” Phys. Rev. Lett. 61, 50–53 (1988). [CrossRef]  

3. Y. H. Shih and C. O. Alley, “New type of Einstein–Podolsky–Rosen–Bohm experiment using pairs of light quanta produced by optical parametric down conversion,” Phys. Rev. Lett. 61, 2921–2924 (1988). [CrossRef]  

4. P. G. Kwiat, K. Mattle, H. Weinfurter, A. Zeilinger, A. V. Sergienko, and Y. Shih, “New high-intensity source of polarization-entangled photon pairs,” Phys. Rev. Lett. 75, 4337–4341 (1995). [CrossRef]  

5. M. A. Horne, A. Shimony, and A. Zeilinger, “Two-particle interferometry,” Phys. Rev. Lett. 62, 2209–2212 (1989). [CrossRef]  

6. J. G. Rarity and P. R. Tapster, “Experimental violation of Bell’s inequality based on phase and momentum,” Phys. Rev. Lett. 64, 2495–2498 (1990). [CrossRef]  

7. A. Mair, A. Vaziri, G. Weihs, and A. Zeilinger, “Entanglement of the orbital angular momentum states of photons,” Nature 412, 313–316 (2001). [CrossRef]  

8. J. D. Franson, “Bell inequality for position and time,” Phys. Rev. Lett. 62, 2205–2208 (1989). [CrossRef]  

9. C. Bernhard, B. Bessire, T. Feurer, and A. Stefanov, “Shaping frequency-entangled qudits,” Phys. Rev. A 88, 032322 (2013). [CrossRef]  

10. L. Olislager, J. Cussey, A. T. Nguyen, P. Emplit, S. Massar, J.-M. Merolla, and K. P. Huy, “Frequency-bin entangled photons,” Phys. Rev. A 82, 013804 (2010). [CrossRef]  

11. L. Olislager, E. Woodhead, K. P. Huy, J.-M. Merolla, P. Emplit, and S. Massar, “Creating and manipulating entangled optical qubits in the frequency domain,” Phys. Rev. A 89, 052323 (2014). [CrossRef]  

12. Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015). [CrossRef]  

13. S. Ramelow, L. Ratschbacher, A. Fedrizzi, N. K. Langford, and A. Zeilinger, “Discrete tunable color entanglement,” Phys. Rev. Lett. 103, 253601 (2009). [CrossRef]  

14. M. Halder, A. Beveratos, N. Gisin, V. Scarani, C. Simon, and H. Zbinden, “Entangling independent photons by time measurement,” Nat. Phys. 3, 692–695 (2007). [CrossRef]  

15. J. S. Bell, “On the Einstein Podolsky Rosen paradox,” Physics 1, 195–200 (1964).

16. J. S. Bell, Speakable and Unspeakable in Quantum Mechanics (Cambridge University, 2004).

17. J. F. Clauser, M. A. Horne, A. Shimony, and R. A. Holt, “Proposed experiment to test local hidden-variable theories,” Phys. Rev. Lett. 23, 880–884 (1969). [CrossRef]  

18. A. Einstein, B. Podolsky, and N. Rosen, “Can quantum-mechanical description of physical reality be considered complete?” Phys. Rev. 47, 777–780 (1935). [CrossRef]  

19. M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015). [CrossRef]  

20. L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015). [CrossRef]  

21. J. Fekete, D. Rielander, M. Cristiani, and H. de Riedmatten, “Ultranarrow-band photon-pair source compatible with solid state quantum memories and telecommunication networks,” Phys. Rev. Lett. 110, 220502 (2013). [CrossRef]  

22. X.-H. Bao, Y. Qian, J. Yang, H. Zhang, Z.-B. Chen, T. Yang, and J.-W. Pan, “Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories,” Phys. Rev. Lett. 101, 190501 (2008). [CrossRef]  

23. C. Shu, P. Chen, T. K. A. Chow, L. Zhu, Y. Xiao, M. M. T. Loy, and S. Du, “Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapor cell,” Nat. Commun. 7, 12783 (2016). [CrossRef]  

24. S. Du, P. Kolchin, C. Belthangady, G. Y. Yin, and S. E. Harris, “Subnatural linewidth biphotons with controllable temporal length,” Phys. Rev. Lett. 100, 183603 (2008). [CrossRef]  

25. L. Zhao, X. Guo, C. Liu, Y. Sun, M. M. T. Loy, and S. Du, “Photon pairs with coherence time exceeding 1 μs,” Optica 1, 84–88 (2014). [CrossRef]  

26. Z. Han, P. Qian, L. Zhou, J. F. Chen, and W. Zhang, “Coherence time limit of the biphotons generated in a dense cold atom cloud,” Sci. Rep. 5, 9126 (2015). [CrossRef]  

27. B. Srivathsan, G. K. Gulati, B. Chng, G. Maslennikov, D. Matsukevich, and C. Kurtsiefer, “Narrow band source of transform-limited photon pairs via four-wave mixing in a cold atomic ensemble,” Phys. Rev. Lett. 111, 123602 (2013). [CrossRef]  

28. K. Liao, H. Yan, J. He, S. Du, Z.-M. Zhang, and S.-L. Zhu, “Subnatural-linewidth polarization-entangled photon pairs with controllable temporal length,” Phys. Rev. Lett. 112, 243602 (2014). [CrossRef]  

29. Y.-W. Cho, K.-K. Park, J.-C. Lee, and Y.-H. Kim, “Engineering frequency-time quantum correlation of narrow-band biphotons from cold atoms,” Phys. Rev. Lett. 113, 063602 (2014). [CrossRef]  

30. P. Chen, C. Shu, X. Guo, M. M. T. Loy, and S. Du, “Measuring the biphoton temporal wave function with polarization-dependent and time-resolved two-photon interference,” Phys. Rev. Lett. 114, 010401 (2015). [CrossRef]  

31. S. Du, “Quantum-state purity of heralded single photons produced from frequency-anticorrelated biphotons,” Phys. Rev. A 92, 043836 (2015). [CrossRef]  

32. P. Qian, Z. Gu, R. Cao, R. Wen, Z. Y. Ou, J. F. Chen, and W. Zhang, “Temporal purity and quantum interference of single photons from two independent cold atomic ensembles,” Phys. Rev. Lett. 117, 013602 (2016). [CrossRef]  

33. T.-M. Zhao, H. Zhang, J. Yang, Z.-R. Sang, X. Jiang, X.-H. Bao, and J.-W. Pan, “Entangling different-color photons via time-resolved measurement and active feed forward,” Phys. Rev. Lett. 112, 103602 (2014). [CrossRef]  

34. S. Zhang, J. F. Chen, C. Liu, S. Zhou, M. M. T. Loy, G. K. L. Wong, and S. Du, “A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth,” Rev. Sci. Instrum. 83, 073102 (2012). [CrossRef]  

35. See the supplementary material and Refs. [31,32,36] for a detailed description of the experimental setup, the theory of SFWM biphoton generation from cold atoms, and the derivation of quantum beating and CHSH Bell parameter from frequency-bin entanglement, the heralded single-photon quantum state, and the biphoton waveform likeness between the two SFWM paths.

36. S. Du, J. Wen, and M. H. Rubin, “Narrowband biphoton generation near atomic resonance,” J. Opt. Soc. Am. B 25, C98–C108 (2008). [CrossRef]  

37. J.-W. Pan, D. Bouwmeester, H. Weinfurter, and A. Zeilinger, “Experimental entanglement swapping: entangling photons that never interacted,” Phys. Rev. Lett. 80, 3891–3894 (1998). [CrossRef]  

38. S. Clemmen, A. Farsi, S. Ramelow, and A. L. Gaeta, “Ramsey interference with single photons,” Phys. Rev. Lett. 117, 223601 (2016). [CrossRef]  

39. H. J. Kimble, “The quantum internet,” Nature 453, 1023–1030 (2008). [CrossRef]  

References

  • View by:
  • |
  • |
  • |

  1. R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, “Quantum entanglement,” Rev. Mod. Phys. 81, 865–942 (2009).
    [Crossref]
  2. Z. Y. Ou and L. Mandel, “Violation of Bell’s inequality and classical probability in a two-photon correlation experiment,” Phys. Rev. Lett. 61, 50–53 (1988).
    [Crossref]
  3. Y. H. Shih and C. O. Alley, “New type of Einstein–Podolsky–Rosen–Bohm experiment using pairs of light quanta produced by optical parametric down conversion,” Phys. Rev. Lett. 61, 2921–2924 (1988).
    [Crossref]
  4. P. G. Kwiat, K. Mattle, H. Weinfurter, A. Zeilinger, A. V. Sergienko, and Y. Shih, “New high-intensity source of polarization-entangled photon pairs,” Phys. Rev. Lett. 75, 4337–4341 (1995).
    [Crossref]
  5. M. A. Horne, A. Shimony, and A. Zeilinger, “Two-particle interferometry,” Phys. Rev. Lett. 62, 2209–2212 (1989).
    [Crossref]
  6. J. G. Rarity and P. R. Tapster, “Experimental violation of Bell’s inequality based on phase and momentum,” Phys. Rev. Lett. 64, 2495–2498 (1990).
    [Crossref]
  7. A. Mair, A. Vaziri, G. Weihs, and A. Zeilinger, “Entanglement of the orbital angular momentum states of photons,” Nature 412, 313–316 (2001).
    [Crossref]
  8. J. D. Franson, “Bell inequality for position and time,” Phys. Rev. Lett. 62, 2205–2208 (1989).
    [Crossref]
  9. C. Bernhard, B. Bessire, T. Feurer, and A. Stefanov, “Shaping frequency-entangled qudits,” Phys. Rev. A 88, 032322 (2013).
    [Crossref]
  10. L. Olislager, J. Cussey, A. T. Nguyen, P. Emplit, S. Massar, J.-M. Merolla, and K. P. Huy, “Frequency-bin entangled photons,” Phys. Rev. A 82, 013804 (2010).
    [Crossref]
  11. L. Olislager, E. Woodhead, K. P. Huy, J.-M. Merolla, P. Emplit, and S. Massar, “Creating and manipulating entangled optical qubits in the frequency domain,” Phys. Rev. A 89, 052323 (2014).
    [Crossref]
  12. Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
    [Crossref]
  13. S. Ramelow, L. Ratschbacher, A. Fedrizzi, N. K. Langford, and A. Zeilinger, “Discrete tunable color entanglement,” Phys. Rev. Lett. 103, 253601 (2009).
    [Crossref]
  14. M. Halder, A. Beveratos, N. Gisin, V. Scarani, C. Simon, and H. Zbinden, “Entangling independent photons by time measurement,” Nat. Phys. 3, 692–695 (2007).
    [Crossref]
  15. J. S. Bell, “On the Einstein Podolsky Rosen paradox,” Physics 1, 195–200 (1964).
  16. J. S. Bell, Speakable and Unspeakable in Quantum Mechanics (Cambridge University, 2004).
  17. J. F. Clauser, M. A. Horne, A. Shimony, and R. A. Holt, “Proposed experiment to test local hidden-variable theories,” Phys. Rev. Lett. 23, 880–884 (1969).
    [Crossref]
  18. A. Einstein, B. Podolsky, and N. Rosen, “Can quantum-mechanical description of physical reality be considered complete?” Phys. Rev. 47, 777–780 (1935).
    [Crossref]
  19. M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
    [Crossref]
  20. L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
    [Crossref]
  21. J. Fekete, D. Rielander, M. Cristiani, and H. de Riedmatten, “Ultranarrow-band photon-pair source compatible with solid state quantum memories and telecommunication networks,” Phys. Rev. Lett. 110, 220502 (2013).
    [Crossref]
  22. X.-H. Bao, Y. Qian, J. Yang, H. Zhang, Z.-B. Chen, T. Yang, and J.-W. Pan, “Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories,” Phys. Rev. Lett. 101, 190501 (2008).
    [Crossref]
  23. C. Shu, P. Chen, T. K. A. Chow, L. Zhu, Y. Xiao, M. M. T. Loy, and S. Du, “Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapor cell,” Nat. Commun. 7, 12783 (2016).
    [Crossref]
  24. S. Du, P. Kolchin, C. Belthangady, G. Y. Yin, and S. E. Harris, “Subnatural linewidth biphotons with controllable temporal length,” Phys. Rev. Lett. 100, 183603 (2008).
    [Crossref]
  25. L. Zhao, X. Guo, C. Liu, Y. Sun, M. M. T. Loy, and S. Du, “Photon pairs with coherence time exceeding 1 μs,” Optica 1, 84–88 (2014).
    [Crossref]
  26. Z. Han, P. Qian, L. Zhou, J. F. Chen, and W. Zhang, “Coherence time limit of the biphotons generated in a dense cold atom cloud,” Sci. Rep. 5, 9126 (2015).
    [Crossref]
  27. B. Srivathsan, G. K. Gulati, B. Chng, G. Maslennikov, D. Matsukevich, and C. Kurtsiefer, “Narrow band source of transform-limited photon pairs via four-wave mixing in a cold atomic ensemble,” Phys. Rev. Lett. 111, 123602 (2013).
    [Crossref]
  28. K. Liao, H. Yan, J. He, S. Du, Z.-M. Zhang, and S.-L. Zhu, “Subnatural-linewidth polarization-entangled photon pairs with controllable temporal length,” Phys. Rev. Lett. 112, 243602 (2014).
    [Crossref]
  29. Y.-W. Cho, K.-K. Park, J.-C. Lee, and Y.-H. Kim, “Engineering frequency-time quantum correlation of narrow-band biphotons from cold atoms,” Phys. Rev. Lett. 113, 063602 (2014).
    [Crossref]
  30. P. Chen, C. Shu, X. Guo, M. M. T. Loy, and S. Du, “Measuring the biphoton temporal wave function with polarization-dependent and time-resolved two-photon interference,” Phys. Rev. Lett. 114, 010401 (2015).
    [Crossref]
  31. S. Du, “Quantum-state purity of heralded single photons produced from frequency-anticorrelated biphotons,” Phys. Rev. A 92, 043836 (2015).
    [Crossref]
  32. P. Qian, Z. Gu, R. Cao, R. Wen, Z. Y. Ou, J. F. Chen, and W. Zhang, “Temporal purity and quantum interference of single photons from two independent cold atomic ensembles,” Phys. Rev. Lett. 117, 013602 (2016).
    [Crossref]
  33. T.-M. Zhao, H. Zhang, J. Yang, Z.-R. Sang, X. Jiang, X.-H. Bao, and J.-W. Pan, “Entangling different-color photons via time-resolved measurement and active feed forward,” Phys. Rev. Lett. 112, 103602 (2014).
    [Crossref]
  34. S. Zhang, J. F. Chen, C. Liu, S. Zhou, M. M. T. Loy, G. K. L. Wong, and S. Du, “A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth,” Rev. Sci. Instrum. 83, 073102 (2012).
    [Crossref]
  35. See the supplementary material and Refs. [31,32,36] for a detailed description of the experimental setup, the theory of SFWM biphoton generation from cold atoms, and the derivation of quantum beating and CHSH Bell parameter from frequency-bin entanglement, the heralded single-photon quantum state, and the biphoton waveform likeness between the two SFWM paths.
  36. S. Du, J. Wen, and M. H. Rubin, “Narrowband biphoton generation near atomic resonance,” J. Opt. Soc. Am. B 25, C98–C108 (2008).
    [Crossref]
  37. J.-W. Pan, D. Bouwmeester, H. Weinfurter, and A. Zeilinger, “Experimental entanglement swapping: entangling photons that never interacted,” Phys. Rev. Lett. 80, 3891–3894 (1998).
    [Crossref]
  38. S. Clemmen, A. Farsi, S. Ramelow, and A. L. Gaeta, “Ramsey interference with single photons,” Phys. Rev. Lett. 117, 223601 (2016).
    [Crossref]
  39. H. J. Kimble, “The quantum internet,” Nature 453, 1023–1030 (2008).
    [Crossref]

2016 (3)

C. Shu, P. Chen, T. K. A. Chow, L. Zhu, Y. Xiao, M. M. T. Loy, and S. Du, “Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapor cell,” Nat. Commun. 7, 12783 (2016).
[Crossref]

P. Qian, Z. Gu, R. Cao, R. Wen, Z. Y. Ou, J. F. Chen, and W. Zhang, “Temporal purity and quantum interference of single photons from two independent cold atomic ensembles,” Phys. Rev. Lett. 117, 013602 (2016).
[Crossref]

S. Clemmen, A. Farsi, S. Ramelow, and A. L. Gaeta, “Ramsey interference with single photons,” Phys. Rev. Lett. 117, 223601 (2016).
[Crossref]

2015 (6)

P. Chen, C. Shu, X. Guo, M. M. T. Loy, and S. Du, “Measuring the biphoton temporal wave function with polarization-dependent and time-resolved two-photon interference,” Phys. Rev. Lett. 114, 010401 (2015).
[Crossref]

S. Du, “Quantum-state purity of heralded single photons produced from frequency-anticorrelated biphotons,” Phys. Rev. A 92, 043836 (2015).
[Crossref]

Z. Han, P. Qian, L. Zhou, J. F. Chen, and W. Zhang, “Coherence time limit of the biphotons generated in a dense cold atom cloud,” Sci. Rep. 5, 9126 (2015).
[Crossref]

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

2014 (5)

L. Olislager, E. Woodhead, K. P. Huy, J.-M. Merolla, P. Emplit, and S. Massar, “Creating and manipulating entangled optical qubits in the frequency domain,” Phys. Rev. A 89, 052323 (2014).
[Crossref]

K. Liao, H. Yan, J. He, S. Du, Z.-M. Zhang, and S.-L. Zhu, “Subnatural-linewidth polarization-entangled photon pairs with controllable temporal length,” Phys. Rev. Lett. 112, 243602 (2014).
[Crossref]

Y.-W. Cho, K.-K. Park, J.-C. Lee, and Y.-H. Kim, “Engineering frequency-time quantum correlation of narrow-band biphotons from cold atoms,” Phys. Rev. Lett. 113, 063602 (2014).
[Crossref]

T.-M. Zhao, H. Zhang, J. Yang, Z.-R. Sang, X. Jiang, X.-H. Bao, and J.-W. Pan, “Entangling different-color photons via time-resolved measurement and active feed forward,” Phys. Rev. Lett. 112, 103602 (2014).
[Crossref]

L. Zhao, X. Guo, C. Liu, Y. Sun, M. M. T. Loy, and S. Du, “Photon pairs with coherence time exceeding 1 μs,” Optica 1, 84–88 (2014).
[Crossref]

2013 (3)

J. Fekete, D. Rielander, M. Cristiani, and H. de Riedmatten, “Ultranarrow-band photon-pair source compatible with solid state quantum memories and telecommunication networks,” Phys. Rev. Lett. 110, 220502 (2013).
[Crossref]

B. Srivathsan, G. K. Gulati, B. Chng, G. Maslennikov, D. Matsukevich, and C. Kurtsiefer, “Narrow band source of transform-limited photon pairs via four-wave mixing in a cold atomic ensemble,” Phys. Rev. Lett. 111, 123602 (2013).
[Crossref]

C. Bernhard, B. Bessire, T. Feurer, and A. Stefanov, “Shaping frequency-entangled qudits,” Phys. Rev. A 88, 032322 (2013).
[Crossref]

2012 (1)

S. Zhang, J. F. Chen, C. Liu, S. Zhou, M. M. T. Loy, G. K. L. Wong, and S. Du, “A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth,” Rev. Sci. Instrum. 83, 073102 (2012).
[Crossref]

2010 (1)

L. Olislager, J. Cussey, A. T. Nguyen, P. Emplit, S. Massar, J.-M. Merolla, and K. P. Huy, “Frequency-bin entangled photons,” Phys. Rev. A 82, 013804 (2010).
[Crossref]

2009 (2)

R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, “Quantum entanglement,” Rev. Mod. Phys. 81, 865–942 (2009).
[Crossref]

S. Ramelow, L. Ratschbacher, A. Fedrizzi, N. K. Langford, and A. Zeilinger, “Discrete tunable color entanglement,” Phys. Rev. Lett. 103, 253601 (2009).
[Crossref]

2008 (4)

S. Du, J. Wen, and M. H. Rubin, “Narrowband biphoton generation near atomic resonance,” J. Opt. Soc. Am. B 25, C98–C108 (2008).
[Crossref]

S. Du, P. Kolchin, C. Belthangady, G. Y. Yin, and S. E. Harris, “Subnatural linewidth biphotons with controllable temporal length,” Phys. Rev. Lett. 100, 183603 (2008).
[Crossref]

X.-H. Bao, Y. Qian, J. Yang, H. Zhang, Z.-B. Chen, T. Yang, and J.-W. Pan, “Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories,” Phys. Rev. Lett. 101, 190501 (2008).
[Crossref]

H. J. Kimble, “The quantum internet,” Nature 453, 1023–1030 (2008).
[Crossref]

2007 (1)

M. Halder, A. Beveratos, N. Gisin, V. Scarani, C. Simon, and H. Zbinden, “Entangling independent photons by time measurement,” Nat. Phys. 3, 692–695 (2007).
[Crossref]

2001 (1)

A. Mair, A. Vaziri, G. Weihs, and A. Zeilinger, “Entanglement of the orbital angular momentum states of photons,” Nature 412, 313–316 (2001).
[Crossref]

1998 (1)

J.-W. Pan, D. Bouwmeester, H. Weinfurter, and A. Zeilinger, “Experimental entanglement swapping: entangling photons that never interacted,” Phys. Rev. Lett. 80, 3891–3894 (1998).
[Crossref]

1995 (1)

P. G. Kwiat, K. Mattle, H. Weinfurter, A. Zeilinger, A. V. Sergienko, and Y. Shih, “New high-intensity source of polarization-entangled photon pairs,” Phys. Rev. Lett. 75, 4337–4341 (1995).
[Crossref]

1990 (1)

J. G. Rarity and P. R. Tapster, “Experimental violation of Bell’s inequality based on phase and momentum,” Phys. Rev. Lett. 64, 2495–2498 (1990).
[Crossref]

1989 (2)

M. A. Horne, A. Shimony, and A. Zeilinger, “Two-particle interferometry,” Phys. Rev. Lett. 62, 2209–2212 (1989).
[Crossref]

J. D. Franson, “Bell inequality for position and time,” Phys. Rev. Lett. 62, 2205–2208 (1989).
[Crossref]

1988 (2)

Z. Y. Ou and L. Mandel, “Violation of Bell’s inequality and classical probability in a two-photon correlation experiment,” Phys. Rev. Lett. 61, 50–53 (1988).
[Crossref]

Y. H. Shih and C. O. Alley, “New type of Einstein–Podolsky–Rosen–Bohm experiment using pairs of light quanta produced by optical parametric down conversion,” Phys. Rev. Lett. 61, 2921–2924 (1988).
[Crossref]

1969 (1)

J. F. Clauser, M. A. Horne, A. Shimony, and R. A. Holt, “Proposed experiment to test local hidden-variable theories,” Phys. Rev. Lett. 23, 880–884 (1969).
[Crossref]

1964 (1)

J. S. Bell, “On the Einstein Podolsky Rosen paradox,” Physics 1, 195–200 (1964).

1935 (1)

A. Einstein, B. Podolsky, and N. Rosen, “Can quantum-mechanical description of physical reality be considered complete?” Phys. Rev. 47, 777–780 (1935).
[Crossref]

Abellan, C.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Alley, C. O.

Y. H. Shih and C. O. Alley, “New type of Einstein–Podolsky–Rosen–Bohm experiment using pairs of light quanta produced by optical parametric down conversion,” Phys. Rev. Lett. 61, 2921–2924 (1988).
[Crossref]

Allman, M. S.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Amaya, W.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Bao, X.-H.

T.-M. Zhao, H. Zhang, J. Yang, Z.-R. Sang, X. Jiang, X.-H. Bao, and J.-W. Pan, “Entangling different-color photons via time-resolved measurement and active feed forward,” Phys. Rev. Lett. 112, 103602 (2014).
[Crossref]

X.-H. Bao, Y. Qian, J. Yang, H. Zhang, Z.-B. Chen, T. Yang, and J.-W. Pan, “Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories,” Phys. Rev. Lett. 101, 190501 (2008).
[Crossref]

Bell, J. S.

J. S. Bell, “On the Einstein Podolsky Rosen paradox,” Physics 1, 195–200 (1964).

J. S. Bell, Speakable and Unspeakable in Quantum Mechanics (Cambridge University, 2004).

Belthangady, C.

S. Du, P. Kolchin, C. Belthangady, G. Y. Yin, and S. E. Harris, “Subnatural linewidth biphotons with controllable temporal length,” Phys. Rev. Lett. 100, 183603 (2008).
[Crossref]

Bernhard, C.

C. Bernhard, B. Bessire, T. Feurer, and A. Stefanov, “Shaping frequency-entangled qudits,” Phys. Rev. A 88, 032322 (2013).
[Crossref]

Bessire, B.

C. Bernhard, B. Bessire, T. Feurer, and A. Stefanov, “Shaping frequency-entangled qudits,” Phys. Rev. A 88, 032322 (2013).
[Crossref]

Beveratos, A.

M. Halder, A. Beveratos, N. Gisin, V. Scarani, C. Simon, and H. Zbinden, “Entangling independent photons by time measurement,” Nat. Phys. 3, 692–695 (2007).
[Crossref]

Beyer, J.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Bienfang, J. C.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

Bierhorst, P.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Bouwmeester, D.

J.-W. Pan, D. Bouwmeester, H. Weinfurter, and A. Zeilinger, “Experimental entanglement swapping: entangling photons that never interacted,” Phys. Rev. Lett. 80, 3891–3894 (1998).
[Crossref]

Cao, R.

P. Qian, Z. Gu, R. Cao, R. Wen, Z. Y. Ou, J. F. Chen, and W. Zhang, “Temporal purity and quantum interference of single photons from two independent cold atomic ensembles,” Phys. Rev. Lett. 117, 013602 (2016).
[Crossref]

Chen, J. F.

P. Qian, Z. Gu, R. Cao, R. Wen, Z. Y. Ou, J. F. Chen, and W. Zhang, “Temporal purity and quantum interference of single photons from two independent cold atomic ensembles,” Phys. Rev. Lett. 117, 013602 (2016).
[Crossref]

Z. Han, P. Qian, L. Zhou, J. F. Chen, and W. Zhang, “Coherence time limit of the biphotons generated in a dense cold atom cloud,” Sci. Rep. 5, 9126 (2015).
[Crossref]

S. Zhang, J. F. Chen, C. Liu, S. Zhou, M. M. T. Loy, G. K. L. Wong, and S. Du, “A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth,” Rev. Sci. Instrum. 83, 073102 (2012).
[Crossref]

Chen, P.

C. Shu, P. Chen, T. K. A. Chow, L. Zhu, Y. Xiao, M. M. T. Loy, and S. Du, “Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapor cell,” Nat. Commun. 7, 12783 (2016).
[Crossref]

P. Chen, C. Shu, X. Guo, M. M. T. Loy, and S. Du, “Measuring the biphoton temporal wave function with polarization-dependent and time-resolved two-photon interference,” Phys. Rev. Lett. 114, 010401 (2015).
[Crossref]

Chen, Z.-B.

X.-H. Bao, Y. Qian, J. Yang, H. Zhang, Z.-B. Chen, T. Yang, and J.-W. Pan, “Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories,” Phys. Rev. Lett. 101, 190501 (2008).
[Crossref]

Chng, B.

B. Srivathsan, G. K. Gulati, B. Chng, G. Maslennikov, D. Matsukevich, and C. Kurtsiefer, “Narrow band source of transform-limited photon pairs via four-wave mixing in a cold atomic ensemble,” Phys. Rev. Lett. 111, 123602 (2013).
[Crossref]

Cho, Y.-W.

Y.-W. Cho, K.-K. Park, J.-C. Lee, and Y.-H. Kim, “Engineering frequency-time quantum correlation of narrow-band biphotons from cold atoms,” Phys. Rev. Lett. 113, 063602 (2014).
[Crossref]

Chow, T. K. A.

C. Shu, P. Chen, T. K. A. Chow, L. Zhu, Y. Xiao, M. M. T. Loy, and S. Du, “Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapor cell,” Nat. Commun. 7, 12783 (2016).
[Crossref]

Christensen, B. G.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Clauser, J. F.

J. F. Clauser, M. A. Horne, A. Shimony, and R. A. Holt, “Proposed experiment to test local hidden-variable theories,” Phys. Rev. Lett. 23, 880–884 (1969).
[Crossref]

Clemmen, S.

S. Clemmen, A. Farsi, S. Ramelow, and A. L. Gaeta, “Ramsey interference with single photons,” Phys. Rev. Lett. 117, 223601 (2016).
[Crossref]

Coakley, K. J.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Cristiani, M.

J. Fekete, D. Rielander, M. Cristiani, and H. de Riedmatten, “Ultranarrow-band photon-pair source compatible with solid state quantum memories and telecommunication networks,” Phys. Rev. Lett. 110, 220502 (2013).
[Crossref]

Cussey, J.

L. Olislager, J. Cussey, A. T. Nguyen, P. Emplit, S. Massar, J.-M. Merolla, and K. P. Huy, “Frequency-bin entangled photons,” Phys. Rev. A 82, 013804 (2010).
[Crossref]

de Riedmatten, H.

J. Fekete, D. Rielander, M. Cristiani, and H. de Riedmatten, “Ultranarrow-band photon-pair source compatible with solid state quantum memories and telecommunication networks,” Phys. Rev. Lett. 110, 220502 (2013).
[Crossref]

Du, S.

C. Shu, P. Chen, T. K. A. Chow, L. Zhu, Y. Xiao, M. M. T. Loy, and S. Du, “Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapor cell,” Nat. Commun. 7, 12783 (2016).
[Crossref]

P. Chen, C. Shu, X. Guo, M. M. T. Loy, and S. Du, “Measuring the biphoton temporal wave function with polarization-dependent and time-resolved two-photon interference,” Phys. Rev. Lett. 114, 010401 (2015).
[Crossref]

S. Du, “Quantum-state purity of heralded single photons produced from frequency-anticorrelated biphotons,” Phys. Rev. A 92, 043836 (2015).
[Crossref]

L. Zhao, X. Guo, C. Liu, Y. Sun, M. M. T. Loy, and S. Du, “Photon pairs with coherence time exceeding 1 μs,” Optica 1, 84–88 (2014).
[Crossref]

K. Liao, H. Yan, J. He, S. Du, Z.-M. Zhang, and S.-L. Zhu, “Subnatural-linewidth polarization-entangled photon pairs with controllable temporal length,” Phys. Rev. Lett. 112, 243602 (2014).
[Crossref]

S. Zhang, J. F. Chen, C. Liu, S. Zhou, M. M. T. Loy, G. K. L. Wong, and S. Du, “A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth,” Rev. Sci. Instrum. 83, 073102 (2012).
[Crossref]

S. Du, J. Wen, and M. H. Rubin, “Narrowband biphoton generation near atomic resonance,” J. Opt. Soc. Am. B 25, C98–C108 (2008).
[Crossref]

S. Du, P. Kolchin, C. Belthangady, G. Y. Yin, and S. E. Harris, “Subnatural linewidth biphotons with controllable temporal length,” Phys. Rev. Lett. 100, 183603 (2008).
[Crossref]

Dyer, S. D.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Einstein, A.

A. Einstein, B. Podolsky, and N. Rosen, “Can quantum-mechanical description of physical reality be considered complete?” Phys. Rev. 47, 777–780 (1935).
[Crossref]

Emplit, P.

L. Olislager, E. Woodhead, K. P. Huy, J.-M. Merolla, P. Emplit, and S. Massar, “Creating and manipulating entangled optical qubits in the frequency domain,” Phys. Rev. A 89, 052323 (2014).
[Crossref]

L. Olislager, J. Cussey, A. T. Nguyen, P. Emplit, S. Massar, J.-M. Merolla, and K. P. Huy, “Frequency-bin entangled photons,” Phys. Rev. A 82, 013804 (2010).
[Crossref]

Farr, W. H.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Farsi, A.

S. Clemmen, A. Farsi, S. Ramelow, and A. L. Gaeta, “Ramsey interference with single photons,” Phys. Rev. Lett. 117, 223601 (2016).
[Crossref]

Fedrizzi, A.

S. Ramelow, L. Ratschbacher, A. Fedrizzi, N. K. Langford, and A. Zeilinger, “Discrete tunable color entanglement,” Phys. Rev. Lett. 103, 253601 (2009).
[Crossref]

Fekete, J.

J. Fekete, D. Rielander, M. Cristiani, and H. de Riedmatten, “Ultranarrow-band photon-pair source compatible with solid state quantum memories and telecommunication networks,” Phys. Rev. Lett. 110, 220502 (2013).
[Crossref]

Feurer, T.

C. Bernhard, B. Bessire, T. Feurer, and A. Stefanov, “Shaping frequency-entangled qudits,” Phys. Rev. A 88, 032322 (2013).
[Crossref]

Franson, J. D.

J. D. Franson, “Bell inequality for position and time,” Phys. Rev. Lett. 62, 2205–2208 (1989).
[Crossref]

Gaeta, A. L.

S. Clemmen, A. Farsi, S. Ramelow, and A. L. Gaeta, “Ramsey interference with single photons,” Phys. Rev. Lett. 117, 223601 (2016).
[Crossref]

Gerrits, T.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Gisin, N.

M. Halder, A. Beveratos, N. Gisin, V. Scarani, C. Simon, and H. Zbinden, “Entangling independent photons by time measurement,” Nat. Phys. 3, 692–695 (2007).
[Crossref]

Giustina, M.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Glancy, S.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Gong, Y.-X.

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

Gu, Z.

P. Qian, Z. Gu, R. Cao, R. Wen, Z. Y. Ou, J. F. Chen, and W. Zhang, “Temporal purity and quantum interference of single photons from two independent cold atomic ensembles,” Phys. Rev. Lett. 117, 013602 (2016).
[Crossref]

Gulati, G. K.

B. Srivathsan, G. K. Gulati, B. Chng, G. Maslennikov, D. Matsukevich, and C. Kurtsiefer, “Narrow band source of transform-limited photon pairs via four-wave mixing in a cold atomic ensemble,” Phys. Rev. Lett. 111, 123602 (2013).
[Crossref]

Guo, X.

P. Chen, C. Shu, X. Guo, M. M. T. Loy, and S. Du, “Measuring the biphoton temporal wave function with polarization-dependent and time-resolved two-photon interference,” Phys. Rev. Lett. 114, 010401 (2015).
[Crossref]

L. Zhao, X. Guo, C. Liu, Y. Sun, M. M. T. Loy, and S. Du, “Photon pairs with coherence time exceeding 1 μs,” Optica 1, 84–88 (2014).
[Crossref]

Halder, M.

M. Halder, A. Beveratos, N. Gisin, V. Scarani, C. Simon, and H. Zbinden, “Entangling independent photons by time measurement,” Nat. Phys. 3, 692–695 (2007).
[Crossref]

Hamel, D. R.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Han, Z.

Z. Han, P. Qian, L. Zhou, J. F. Chen, and W. Zhang, “Coherence time limit of the biphotons generated in a dense cold atom cloud,” Sci. Rep. 5, 9126 (2015).
[Crossref]

Handsteiner, J.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Harris, S. E.

S. Du, P. Kolchin, C. Belthangady, G. Y. Yin, and S. E. Harris, “Subnatural linewidth biphotons with controllable temporal length,” Phys. Rev. Lett. 100, 183603 (2008).
[Crossref]

He, J.

K. Liao, H. Yan, J. He, S. Du, Z.-M. Zhang, and S.-L. Zhu, “Subnatural-linewidth polarization-entangled photon pairs with controllable temporal length,” Phys. Rev. Lett. 112, 243602 (2014).
[Crossref]

Hochrainer, A.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Hodge, C.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Holt, R. A.

J. F. Clauser, M. A. Horne, A. Shimony, and R. A. Holt, “Proposed experiment to test local hidden-variable theories,” Phys. Rev. Lett. 23, 880–884 (1969).
[Crossref]

Horne, M. A.

M. A. Horne, A. Shimony, and A. Zeilinger, “Two-particle interferometry,” Phys. Rev. Lett. 62, 2209–2212 (1989).
[Crossref]

J. F. Clauser, M. A. Horne, A. Shimony, and R. A. Holt, “Proposed experiment to test local hidden-variable theories,” Phys. Rev. Lett. 23, 880–884 (1969).
[Crossref]

Horodecki, K.

R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, “Quantum entanglement,” Rev. Mod. Phys. 81, 865–942 (2009).
[Crossref]

Horodecki, M.

R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, “Quantum entanglement,” Rev. Mod. Phys. 81, 865–942 (2009).
[Crossref]

Horodecki, P.

R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, “Quantum entanglement,” Rev. Mod. Phys. 81, 865–942 (2009).
[Crossref]

Horodecki, R.

R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, “Quantum entanglement,” Rev. Mod. Phys. 81, 865–942 (2009).
[Crossref]

Huy, K. P.

L. Olislager, E. Woodhead, K. P. Huy, J.-M. Merolla, P. Emplit, and S. Massar, “Creating and manipulating entangled optical qubits in the frequency domain,” Phys. Rev. A 89, 052323 (2014).
[Crossref]

L. Olislager, J. Cussey, A. T. Nguyen, P. Emplit, S. Massar, J.-M. Merolla, and K. P. Huy, “Frequency-bin entangled photons,” Phys. Rev. A 82, 013804 (2010).
[Crossref]

Jennewein, T.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Jiang, X.

T.-M. Zhao, H. Zhang, J. Yang, Z.-R. Sang, X. Jiang, X.-H. Bao, and J.-W. Pan, “Entangling different-color photons via time-resolved measurement and active feed forward,” Phys. Rev. Lett. 112, 103602 (2014).
[Crossref]

Kim, Y.-H.

Y.-W. Cho, K.-K. Park, J.-C. Lee, and Y.-H. Kim, “Engineering frequency-time quantum correlation of narrow-band biphotons from cold atoms,” Phys. Rev. Lett. 113, 063602 (2014).
[Crossref]

Kimble, H. J.

H. J. Kimble, “The quantum internet,” Nature 453, 1023–1030 (2008).
[Crossref]

Knill, E.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Kofler, J.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Kolchin, P.

S. Du, P. Kolchin, C. Belthangady, G. Y. Yin, and S. E. Harris, “Subnatural linewidth biphotons with controllable temporal length,” Phys. Rev. Lett. 100, 183603 (2008).
[Crossref]

Kumor, D. R.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Kurtsiefer, C.

B. Srivathsan, G. K. Gulati, B. Chng, G. Maslennikov, D. Matsukevich, and C. Kurtsiefer, “Narrow band source of transform-limited photon pairs via four-wave mixing in a cold atomic ensemble,” Phys. Rev. Lett. 111, 123602 (2013).
[Crossref]

Kwiat, P. G.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

P. G. Kwiat, K. Mattle, H. Weinfurter, A. Zeilinger, A. V. Sergienko, and Y. Shih, “New high-intensity source of polarization-entangled photon pairs,” Phys. Rev. Lett. 75, 4337–4341 (1995).
[Crossref]

Lambrocco, C.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Langford, N. K.

S. Ramelow, L. Ratschbacher, A. Fedrizzi, N. K. Langford, and A. Zeilinger, “Discrete tunable color entanglement,” Phys. Rev. Lett. 103, 253601 (2009).
[Crossref]

Larsson, J.-A.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Lee, J.-C.

Y.-W. Cho, K.-K. Park, J.-C. Lee, and Y.-H. Kim, “Engineering frequency-time quantum correlation of narrow-band biphotons from cold atoms,” Phys. Rev. Lett. 113, 063602 (2014).
[Crossref]

Liang, J.

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

Liao, K.

K. Liao, H. Yan, J. He, S. Du, Z.-M. Zhang, and S.-L. Zhu, “Subnatural-linewidth polarization-entangled photon pairs with controllable temporal length,” Phys. Rev. Lett. 112, 243602 (2014).
[Crossref]

Lita, A. E.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Liu, C.

L. Zhao, X. Guo, C. Liu, Y. Sun, M. M. T. Loy, and S. Du, “Photon pairs with coherence time exceeding 1 μs,” Optica 1, 84–88 (2014).
[Crossref]

S. Zhang, J. F. Chen, C. Liu, S. Zhou, M. M. T. Loy, G. K. L. Wong, and S. Du, “A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth,” Rev. Sci. Instrum. 83, 073102 (2012).
[Crossref]

Loy, M. M. T.

C. Shu, P. Chen, T. K. A. Chow, L. Zhu, Y. Xiao, M. M. T. Loy, and S. Du, “Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapor cell,” Nat. Commun. 7, 12783 (2016).
[Crossref]

P. Chen, C. Shu, X. Guo, M. M. T. Loy, and S. Du, “Measuring the biphoton temporal wave function with polarization-dependent and time-resolved two-photon interference,” Phys. Rev. Lett. 114, 010401 (2015).
[Crossref]

L. Zhao, X. Guo, C. Liu, Y. Sun, M. M. T. Loy, and S. Du, “Photon pairs with coherence time exceeding 1 μs,” Optica 1, 84–88 (2014).
[Crossref]

S. Zhang, J. F. Chen, C. Liu, S. Zhou, M. M. T. Loy, G. K. L. Wong, and S. Du, “A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth,” Rev. Sci. Instrum. 83, 073102 (2012).
[Crossref]

Mair, A.

A. Mair, A. Vaziri, G. Weihs, and A. Zeilinger, “Entanglement of the orbital angular momentum states of photons,” Nature 412, 313–316 (2001).
[Crossref]

Mandel, L.

Z. Y. Ou and L. Mandel, “Violation of Bell’s inequality and classical probability in a two-photon correlation experiment,” Phys. Rev. Lett. 61, 50–53 (1988).
[Crossref]

Marsili, F.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Maslennikov, G.

B. Srivathsan, G. K. Gulati, B. Chng, G. Maslennikov, D. Matsukevich, and C. Kurtsiefer, “Narrow band source of transform-limited photon pairs via four-wave mixing in a cold atomic ensemble,” Phys. Rev. Lett. 111, 123602 (2013).
[Crossref]

Massar, S.

L. Olislager, E. Woodhead, K. P. Huy, J.-M. Merolla, P. Emplit, and S. Massar, “Creating and manipulating entangled optical qubits in the frequency domain,” Phys. Rev. A 89, 052323 (2014).
[Crossref]

L. Olislager, J. Cussey, A. T. Nguyen, P. Emplit, S. Massar, J.-M. Merolla, and K. P. Huy, “Frequency-bin entangled photons,” Phys. Rev. A 82, 013804 (2010).
[Crossref]

Matsukevich, D.

B. Srivathsan, G. K. Gulati, B. Chng, G. Maslennikov, D. Matsukevich, and C. Kurtsiefer, “Narrow band source of transform-limited photon pairs via four-wave mixing in a cold atomic ensemble,” Phys. Rev. Lett. 111, 123602 (2013).
[Crossref]

Mattle, K.

P. G. Kwiat, K. Mattle, H. Weinfurter, A. Zeilinger, A. V. Sergienko, and Y. Shih, “New high-intensity source of polarization-entangled photon pairs,” Phys. Rev. Lett. 75, 4337–4341 (1995).
[Crossref]

Merolla, J.-M.

L. Olislager, E. Woodhead, K. P. Huy, J.-M. Merolla, P. Emplit, and S. Massar, “Creating and manipulating entangled optical qubits in the frequency domain,” Phys. Rev. A 89, 052323 (2014).
[Crossref]

L. Olislager, J. Cussey, A. T. Nguyen, P. Emplit, S. Massar, J.-M. Merolla, and K. P. Huy, “Frequency-bin entangled photons,” Phys. Rev. A 82, 013804 (2010).
[Crossref]

Meyer-Scott, E.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Migdall, A. L.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Mirin, R. P.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Mitchell, M. W.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Nam, S. W.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Nguyen, A. T.

L. Olislager, J. Cussey, A. T. Nguyen, P. Emplit, S. Massar, J.-M. Merolla, and K. P. Huy, “Frequency-bin entangled photons,” Phys. Rev. A 82, 013804 (2010).
[Crossref]

Olislager, L.

L. Olislager, E. Woodhead, K. P. Huy, J.-M. Merolla, P. Emplit, and S. Massar, “Creating and manipulating entangled optical qubits in the frequency domain,” Phys. Rev. A 89, 052323 (2014).
[Crossref]

L. Olislager, J. Cussey, A. T. Nguyen, P. Emplit, S. Massar, J.-M. Merolla, and K. P. Huy, “Frequency-bin entangled photons,” Phys. Rev. A 82, 013804 (2010).
[Crossref]

Ou, Z. Y.

P. Qian, Z. Gu, R. Cao, R. Wen, Z. Y. Ou, J. F. Chen, and W. Zhang, “Temporal purity and quantum interference of single photons from two independent cold atomic ensembles,” Phys. Rev. Lett. 117, 013602 (2016).
[Crossref]

Z. Y. Ou and L. Mandel, “Violation of Bell’s inequality and classical probability in a two-photon correlation experiment,” Phys. Rev. Lett. 61, 50–53 (1988).
[Crossref]

Pan, J.-W.

T.-M. Zhao, H. Zhang, J. Yang, Z.-R. Sang, X. Jiang, X.-H. Bao, and J.-W. Pan, “Entangling different-color photons via time-resolved measurement and active feed forward,” Phys. Rev. Lett. 112, 103602 (2014).
[Crossref]

X.-H. Bao, Y. Qian, J. Yang, H. Zhang, Z.-B. Chen, T. Yang, and J.-W. Pan, “Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories,” Phys. Rev. Lett. 101, 190501 (2008).
[Crossref]

J.-W. Pan, D. Bouwmeester, H. Weinfurter, and A. Zeilinger, “Experimental entanglement swapping: entangling photons that never interacted,” Phys. Rev. Lett. 80, 3891–3894 (1998).
[Crossref]

Park, K.-K.

Y.-W. Cho, K.-K. Park, J.-C. Lee, and Y.-H. Kim, “Engineering frequency-time quantum correlation of narrow-band biphotons from cold atoms,” Phys. Rev. Lett. 113, 063602 (2014).
[Crossref]

Phelan, K.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Podolsky, B.

A. Einstein, B. Podolsky, and N. Rosen, “Can quantum-mechanical description of physical reality be considered complete?” Phys. Rev. 47, 777–780 (1935).
[Crossref]

Pruneri, V.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Qian, P.

P. Qian, Z. Gu, R. Cao, R. Wen, Z. Y. Ou, J. F. Chen, and W. Zhang, “Temporal purity and quantum interference of single photons from two independent cold atomic ensembles,” Phys. Rev. Lett. 117, 013602 (2016).
[Crossref]

Z. Han, P. Qian, L. Zhou, J. F. Chen, and W. Zhang, “Coherence time limit of the biphotons generated in a dense cold atom cloud,” Sci. Rep. 5, 9126 (2015).
[Crossref]

Qian, Y.

X.-H. Bao, Y. Qian, J. Yang, H. Zhang, Z.-B. Chen, T. Yang, and J.-W. Pan, “Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories,” Phys. Rev. Lett. 101, 190501 (2008).
[Crossref]

Ramelow, S.

S. Clemmen, A. Farsi, S. Ramelow, and A. L. Gaeta, “Ramsey interference with single photons,” Phys. Rev. Lett. 117, 223601 (2016).
[Crossref]

S. Ramelow, L. Ratschbacher, A. Fedrizzi, N. K. Langford, and A. Zeilinger, “Discrete tunable color entanglement,” Phys. Rev. Lett. 103, 253601 (2009).
[Crossref]

Rarity, J. G.

J. G. Rarity and P. R. Tapster, “Experimental violation of Bell’s inequality based on phase and momentum,” Phys. Rev. Lett. 64, 2495–2498 (1990).
[Crossref]

Ratschbacher, L.

S. Ramelow, L. Ratschbacher, A. Fedrizzi, N. K. Langford, and A. Zeilinger, “Discrete tunable color entanglement,” Phys. Rev. Lett. 103, 253601 (2009).
[Crossref]

Restelli, A.

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

Rielander, D.

J. Fekete, D. Rielander, M. Cristiani, and H. de Riedmatten, “Ultranarrow-band photon-pair source compatible with solid state quantum memories and telecommunication networks,” Phys. Rev. Lett. 110, 220502 (2013).
[Crossref]

Rosen, N.

A. Einstein, B. Podolsky, and N. Rosen, “Can quantum-mechanical description of physical reality be considered complete?” Phys. Rev. 47, 777–780 (1935).
[Crossref]

Rubin, M. H.

Sang, Z.-R.

T.-M. Zhao, H. Zhang, J. Yang, Z.-R. Sang, X. Jiang, X.-H. Bao, and J.-W. Pan, “Entangling different-color photons via time-resolved measurement and active feed forward,” Phys. Rev. Lett. 112, 103602 (2014).
[Crossref]

Scarani, V.

M. Halder, A. Beveratos, N. Gisin, V. Scarani, C. Simon, and H. Zbinden, “Entangling independent photons by time measurement,” Nat. Phys. 3, 692–695 (2007).
[Crossref]

Scheidl, T.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Sergienko, A. V.

P. G. Kwiat, K. Mattle, H. Weinfurter, A. Zeilinger, A. V. Sergienko, and Y. Shih, “New high-intensity source of polarization-entangled photon pairs,” Phys. Rev. Lett. 75, 4337–4341 (1995).
[Crossref]

Shalm, L. K.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Shapiro, J. H.

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

Shaw, M. D.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Shih, Y.

P. G. Kwiat, K. Mattle, H. Weinfurter, A. Zeilinger, A. V. Sergienko, and Y. Shih, “New high-intensity source of polarization-entangled photon pairs,” Phys. Rev. Lett. 75, 4337–4341 (1995).
[Crossref]

Shih, Y. H.

Y. H. Shih and C. O. Alley, “New type of Einstein–Podolsky–Rosen–Bohm experiment using pairs of light quanta produced by optical parametric down conversion,” Phys. Rev. Lett. 61, 2921–2924 (1988).
[Crossref]

Shimony, A.

M. A. Horne, A. Shimony, and A. Zeilinger, “Two-particle interferometry,” Phys. Rev. Lett. 62, 2209–2212 (1989).
[Crossref]

J. F. Clauser, M. A. Horne, A. Shimony, and R. A. Holt, “Proposed experiment to test local hidden-variable theories,” Phys. Rev. Lett. 23, 880–884 (1969).
[Crossref]

Shrestha, S.

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

Shu, C.

C. Shu, P. Chen, T. K. A. Chow, L. Zhu, Y. Xiao, M. M. T. Loy, and S. Du, “Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapor cell,” Nat. Commun. 7, 12783 (2016).
[Crossref]

P. Chen, C. Shu, X. Guo, M. M. T. Loy, and S. Du, “Measuring the biphoton temporal wave function with polarization-dependent and time-resolved two-photon interference,” Phys. Rev. Lett. 114, 010401 (2015).
[Crossref]

Simon, C.

M. Halder, A. Beveratos, N. Gisin, V. Scarani, C. Simon, and H. Zbinden, “Entangling independent photons by time measurement,” Nat. Phys. 3, 692–695 (2007).
[Crossref]

Srivathsan, B.

B. Srivathsan, G. K. Gulati, B. Chng, G. Maslennikov, D. Matsukevich, and C. Kurtsiefer, “Narrow band source of transform-limited photon pairs via four-wave mixing in a cold atomic ensemble,” Phys. Rev. Lett. 111, 123602 (2013).
[Crossref]

Stefanov, A.

C. Bernhard, B. Bessire, T. Feurer, and A. Stefanov, “Shaping frequency-entangled qudits,” Phys. Rev. A 88, 032322 (2013).
[Crossref]

Steinlechner, F.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Stern, J. A.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Stevens, M. J.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Sun, Y.

Tapster, P. R.

J. G. Rarity and P. R. Tapster, “Experimental violation of Bell’s inequality based on phase and momentum,” Phys. Rev. Lett. 64, 2495–2498 (1990).
[Crossref]

Tortorici, E.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Ursin, R.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Vaziri, A.

A. Mair, A. Vaziri, G. Weihs, and A. Zeilinger, “Entanglement of the orbital angular momentum states of photons,” Nature 412, 313–316 (2001).
[Crossref]

Verma, V. B.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Versteegh, M. A. M.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Wayne, M. A.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Weihs, G.

A. Mair, A. Vaziri, G. Weihs, and A. Zeilinger, “Entanglement of the orbital angular momentum states of photons,” Nature 412, 313–316 (2001).
[Crossref]

Weinfurter, H.

J.-W. Pan, D. Bouwmeester, H. Weinfurter, and A. Zeilinger, “Experimental entanglement swapping: entangling photons that never interacted,” Phys. Rev. Lett. 80, 3891–3894 (1998).
[Crossref]

P. G. Kwiat, K. Mattle, H. Weinfurter, A. Zeilinger, A. V. Sergienko, and Y. Shih, “New high-intensity source of polarization-entangled photon pairs,” Phys. Rev. Lett. 75, 4337–4341 (1995).
[Crossref]

Wen, J.

Wen, R.

P. Qian, Z. Gu, R. Cao, R. Wen, Z. Y. Ou, J. F. Chen, and W. Zhang, “Temporal purity and quantum interference of single photons from two independent cold atomic ensembles,” Phys. Rev. Lett. 117, 013602 (2016).
[Crossref]

Wengerowsky, S.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Wittmann, B.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

Wong, C. W.

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

Wong, F. N. C.

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

Wong, G. K. L.

S. Zhang, J. F. Chen, C. Liu, S. Zhou, M. M. T. Loy, G. K. L. Wong, and S. Du, “A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth,” Rev. Sci. Instrum. 83, 073102 (2012).
[Crossref]

Woodhead, E.

L. Olislager, E. Woodhead, K. P. Huy, J.-M. Merolla, P. Emplit, and S. Massar, “Creating and manipulating entangled optical qubits in the frequency domain,” Phys. Rev. A 89, 052323 (2014).
[Crossref]

Xiao, Y.

C. Shu, P. Chen, T. K. A. Chow, L. Zhu, Y. Xiao, M. M. T. Loy, and S. Du, “Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapor cell,” Nat. Commun. 7, 12783 (2016).
[Crossref]

Xie, Z.

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

Xu, X.

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

Yan, H.

K. Liao, H. Yan, J. He, S. Du, Z.-M. Zhang, and S.-L. Zhu, “Subnatural-linewidth polarization-entangled photon pairs with controllable temporal length,” Phys. Rev. Lett. 112, 243602 (2014).
[Crossref]

Yang, J.

T.-M. Zhao, H. Zhang, J. Yang, Z.-R. Sang, X. Jiang, X.-H. Bao, and J.-W. Pan, “Entangling different-color photons via time-resolved measurement and active feed forward,” Phys. Rev. Lett. 112, 103602 (2014).
[Crossref]

X.-H. Bao, Y. Qian, J. Yang, H. Zhang, Z.-B. Chen, T. Yang, and J.-W. Pan, “Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories,” Phys. Rev. Lett. 101, 190501 (2008).
[Crossref]

Yang, T.

X.-H. Bao, Y. Qian, J. Yang, H. Zhang, Z.-B. Chen, T. Yang, and J.-W. Pan, “Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories,” Phys. Rev. Lett. 101, 190501 (2008).
[Crossref]

Yin, G. Y.

S. Du, P. Kolchin, C. Belthangady, G. Y. Yin, and S. E. Harris, “Subnatural linewidth biphotons with controllable temporal length,” Phys. Rev. Lett. 100, 183603 (2008).
[Crossref]

Zbinden, H.

M. Halder, A. Beveratos, N. Gisin, V. Scarani, C. Simon, and H. Zbinden, “Entangling independent photons by time measurement,” Nat. Phys. 3, 692–695 (2007).
[Crossref]

Zeilinger, A.

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

S. Ramelow, L. Ratschbacher, A. Fedrizzi, N. K. Langford, and A. Zeilinger, “Discrete tunable color entanglement,” Phys. Rev. Lett. 103, 253601 (2009).
[Crossref]

A. Mair, A. Vaziri, G. Weihs, and A. Zeilinger, “Entanglement of the orbital angular momentum states of photons,” Nature 412, 313–316 (2001).
[Crossref]

J.-W. Pan, D. Bouwmeester, H. Weinfurter, and A. Zeilinger, “Experimental entanglement swapping: entangling photons that never interacted,” Phys. Rev. Lett. 80, 3891–3894 (1998).
[Crossref]

P. G. Kwiat, K. Mattle, H. Weinfurter, A. Zeilinger, A. V. Sergienko, and Y. Shih, “New high-intensity source of polarization-entangled photon pairs,” Phys. Rev. Lett. 75, 4337–4341 (1995).
[Crossref]

M. A. Horne, A. Shimony, and A. Zeilinger, “Two-particle interferometry,” Phys. Rev. Lett. 62, 2209–2212 (1989).
[Crossref]

Zhang, H.

T.-M. Zhao, H. Zhang, J. Yang, Z.-R. Sang, X. Jiang, X.-H. Bao, and J.-W. Pan, “Entangling different-color photons via time-resolved measurement and active feed forward,” Phys. Rev. Lett. 112, 103602 (2014).
[Crossref]

X.-H. Bao, Y. Qian, J. Yang, H. Zhang, Z.-B. Chen, T. Yang, and J.-W. Pan, “Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories,” Phys. Rev. Lett. 101, 190501 (2008).
[Crossref]

Zhang, S.

S. Zhang, J. F. Chen, C. Liu, S. Zhou, M. M. T. Loy, G. K. L. Wong, and S. Du, “A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth,” Rev. Sci. Instrum. 83, 073102 (2012).
[Crossref]

Zhang, W.

P. Qian, Z. Gu, R. Cao, R. Wen, Z. Y. Ou, J. F. Chen, and W. Zhang, “Temporal purity and quantum interference of single photons from two independent cold atomic ensembles,” Phys. Rev. Lett. 117, 013602 (2016).
[Crossref]

Z. Han, P. Qian, L. Zhou, J. F. Chen, and W. Zhang, “Coherence time limit of the biphotons generated in a dense cold atom cloud,” Sci. Rep. 5, 9126 (2015).
[Crossref]

Zhang, Y.

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

Zhang, Z.-M.

K. Liao, H. Yan, J. He, S. Du, Z.-M. Zhang, and S.-L. Zhu, “Subnatural-linewidth polarization-entangled photon pairs with controllable temporal length,” Phys. Rev. Lett. 112, 243602 (2014).
[Crossref]

Zhao, L.

Zhao, T.-M.

T.-M. Zhao, H. Zhang, J. Yang, Z.-R. Sang, X. Jiang, X.-H. Bao, and J.-W. Pan, “Entangling different-color photons via time-resolved measurement and active feed forward,” Phys. Rev. Lett. 112, 103602 (2014).
[Crossref]

Zhong, T.

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

Zhou, L.

Z. Han, P. Qian, L. Zhou, J. F. Chen, and W. Zhang, “Coherence time limit of the biphotons generated in a dense cold atom cloud,” Sci. Rep. 5, 9126 (2015).
[Crossref]

Zhou, S.

S. Zhang, J. F. Chen, C. Liu, S. Zhou, M. M. T. Loy, G. K. L. Wong, and S. Du, “A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth,” Rev. Sci. Instrum. 83, 073102 (2012).
[Crossref]

Zhu, L.

C. Shu, P. Chen, T. K. A. Chow, L. Zhu, Y. Xiao, M. M. T. Loy, and S. Du, “Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapor cell,” Nat. Commun. 7, 12783 (2016).
[Crossref]

Zhu, S.-L.

K. Liao, H. Yan, J. He, S. Du, Z.-M. Zhang, and S.-L. Zhu, “Subnatural-linewidth polarization-entangled photon pairs with controllable temporal length,” Phys. Rev. Lett. 112, 243602 (2014).
[Crossref]

J. Opt. Soc. Am. B (1)

Nat. Commun. (1)

C. Shu, P. Chen, T. K. A. Chow, L. Zhu, Y. Xiao, M. M. T. Loy, and S. Du, “Subnatural-linewidth biphotons from a Doppler-broadened hot atomic vapor cell,” Nat. Commun. 7, 12783 (2016).
[Crossref]

Nat. Photonics (1)

Z. Xie, T. Zhong, S. Shrestha, X. Xu, J. Liang, Y.-X. Gong, J. C. Bienfang, A. Restelli, J. H. Shapiro, F. N. C. Wong, and C. W. Wong, “Harnessing high-dimensional hyperentanglement through a biphoton frequency comb,” Nat. Photonics 9, 536–542 (2015).
[Crossref]

Nat. Phys. (1)

M. Halder, A. Beveratos, N. Gisin, V. Scarani, C. Simon, and H. Zbinden, “Entangling independent photons by time measurement,” Nat. Phys. 3, 692–695 (2007).
[Crossref]

Nature (2)

A. Mair, A. Vaziri, G. Weihs, and A. Zeilinger, “Entanglement of the orbital angular momentum states of photons,” Nature 412, 313–316 (2001).
[Crossref]

H. J. Kimble, “The quantum internet,” Nature 453, 1023–1030 (2008).
[Crossref]

Optica (1)

Phys. Rev. (1)

A. Einstein, B. Podolsky, and N. Rosen, “Can quantum-mechanical description of physical reality be considered complete?” Phys. Rev. 47, 777–780 (1935).
[Crossref]

Phys. Rev. A (4)

C. Bernhard, B. Bessire, T. Feurer, and A. Stefanov, “Shaping frequency-entangled qudits,” Phys. Rev. A 88, 032322 (2013).
[Crossref]

L. Olislager, J. Cussey, A. T. Nguyen, P. Emplit, S. Massar, J.-M. Merolla, and K. P. Huy, “Frequency-bin entangled photons,” Phys. Rev. A 82, 013804 (2010).
[Crossref]

L. Olislager, E. Woodhead, K. P. Huy, J.-M. Merolla, P. Emplit, and S. Massar, “Creating and manipulating entangled optical qubits in the frequency domain,” Phys. Rev. A 89, 052323 (2014).
[Crossref]

S. Du, “Quantum-state purity of heralded single photons produced from frequency-anticorrelated biphotons,” Phys. Rev. A 92, 043836 (2015).
[Crossref]

Phys. Rev. Lett. (21)

P. Qian, Z. Gu, R. Cao, R. Wen, Z. Y. Ou, J. F. Chen, and W. Zhang, “Temporal purity and quantum interference of single photons from two independent cold atomic ensembles,” Phys. Rev. Lett. 117, 013602 (2016).
[Crossref]

T.-M. Zhao, H. Zhang, J. Yang, Z.-R. Sang, X. Jiang, X.-H. Bao, and J.-W. Pan, “Entangling different-color photons via time-resolved measurement and active feed forward,” Phys. Rev. Lett. 112, 103602 (2014).
[Crossref]

J.-W. Pan, D. Bouwmeester, H. Weinfurter, and A. Zeilinger, “Experimental entanglement swapping: entangling photons that never interacted,” Phys. Rev. Lett. 80, 3891–3894 (1998).
[Crossref]

S. Clemmen, A. Farsi, S. Ramelow, and A. L. Gaeta, “Ramsey interference with single photons,” Phys. Rev. Lett. 117, 223601 (2016).
[Crossref]

S. Du, P. Kolchin, C. Belthangady, G. Y. Yin, and S. E. Harris, “Subnatural linewidth biphotons with controllable temporal length,” Phys. Rev. Lett. 100, 183603 (2008).
[Crossref]

J. F. Clauser, M. A. Horne, A. Shimony, and R. A. Holt, “Proposed experiment to test local hidden-variable theories,” Phys. Rev. Lett. 23, 880–884 (1969).
[Crossref]

B. Srivathsan, G. K. Gulati, B. Chng, G. Maslennikov, D. Matsukevich, and C. Kurtsiefer, “Narrow band source of transform-limited photon pairs via four-wave mixing in a cold atomic ensemble,” Phys. Rev. Lett. 111, 123602 (2013).
[Crossref]

K. Liao, H. Yan, J. He, S. Du, Z.-M. Zhang, and S.-L. Zhu, “Subnatural-linewidth polarization-entangled photon pairs with controllable temporal length,” Phys. Rev. Lett. 112, 243602 (2014).
[Crossref]

Y.-W. Cho, K.-K. Park, J.-C. Lee, and Y.-H. Kim, “Engineering frequency-time quantum correlation of narrow-band biphotons from cold atoms,” Phys. Rev. Lett. 113, 063602 (2014).
[Crossref]

P. Chen, C. Shu, X. Guo, M. M. T. Loy, and S. Du, “Measuring the biphoton temporal wave function with polarization-dependent and time-resolved two-photon interference,” Phys. Rev. Lett. 114, 010401 (2015).
[Crossref]

J. D. Franson, “Bell inequality for position and time,” Phys. Rev. Lett. 62, 2205–2208 (1989).
[Crossref]

Z. Y. Ou and L. Mandel, “Violation of Bell’s inequality and classical probability in a two-photon correlation experiment,” Phys. Rev. Lett. 61, 50–53 (1988).
[Crossref]

Y. H. Shih and C. O. Alley, “New type of Einstein–Podolsky–Rosen–Bohm experiment using pairs of light quanta produced by optical parametric down conversion,” Phys. Rev. Lett. 61, 2921–2924 (1988).
[Crossref]

P. G. Kwiat, K. Mattle, H. Weinfurter, A. Zeilinger, A. V. Sergienko, and Y. Shih, “New high-intensity source of polarization-entangled photon pairs,” Phys. Rev. Lett. 75, 4337–4341 (1995).
[Crossref]

M. A. Horne, A. Shimony, and A. Zeilinger, “Two-particle interferometry,” Phys. Rev. Lett. 62, 2209–2212 (1989).
[Crossref]

J. G. Rarity and P. R. Tapster, “Experimental violation of Bell’s inequality based on phase and momentum,” Phys. Rev. Lett. 64, 2495–2498 (1990).
[Crossref]

M. Giustina, M. A. M. Versteegh, S. Wengerowsky, J. Handsteiner, A. Hochrainer, K. Phelan, F. Steinlechner, J. Kofler, J.-A. Larsson, C. Abellan, W. Amaya, V. Pruneri, M. W. Mitchell, J. Beyer, T. Gerrits, A. E. Lita, L. K. Shalm, S. W. Nam, T. Scheidl, R. Ursin, B. Wittmann, and A. Zeilinger, “Significant-loophole-free test of Bell’s theorem with entangled photons,” Phys. Rev. Lett. 115, 250401 (2015).
[Crossref]

L. K. Shalm, E. Meyer-Scott, B. G. Christensen, P. Bierhorst, M. A. Wayne, M. J. Stevens, T. Gerrits, S. Glancy, D. R. Hamel, M. S. Allman, K. J. Coakley, S. D. Dyer, C. Hodge, A. E. Lita, V. B. Verma, C. Lambrocco, E. Tortorici, A. L. Migdall, Y. Zhang, D. R. Kumor, W. H. Farr, F. Marsili, M. D. Shaw, J. A. Stern, C. Abellan, W. Amaya, V. Pruneri, T. Jennewein, M. W. Mitchell, P. G. Kwiat, J. C. Bienfang, R. P. Mirin, E. Knill, and S. W. Nam, “Strong loophole-free test of local realism,” Phys. Rev. Lett. 115, 250402 (2015).
[Crossref]

J. Fekete, D. Rielander, M. Cristiani, and H. de Riedmatten, “Ultranarrow-band photon-pair source compatible with solid state quantum memories and telecommunication networks,” Phys. Rev. Lett. 110, 220502 (2013).
[Crossref]

X.-H. Bao, Y. Qian, J. Yang, H. Zhang, Z.-B. Chen, T. Yang, and J.-W. Pan, “Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories,” Phys. Rev. Lett. 101, 190501 (2008).
[Crossref]

S. Ramelow, L. Ratschbacher, A. Fedrizzi, N. K. Langford, and A. Zeilinger, “Discrete tunable color entanglement,” Phys. Rev. Lett. 103, 253601 (2009).
[Crossref]

Physics (1)

J. S. Bell, “On the Einstein Podolsky Rosen paradox,” Physics 1, 195–200 (1964).

Rev. Mod. Phys. (1)

R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, “Quantum entanglement,” Rev. Mod. Phys. 81, 865–942 (2009).
[Crossref]

Rev. Sci. Instrum. (1)

S. Zhang, J. F. Chen, C. Liu, S. Zhou, M. M. T. Loy, G. K. L. Wong, and S. Du, “A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth,” Rev. Sci. Instrum. 83, 073102 (2012).
[Crossref]

Sci. Rep. (1)

Z. Han, P. Qian, L. Zhou, J. F. Chen, and W. Zhang, “Coherence time limit of the biphotons generated in a dense cold atom cloud,” Sci. Rep. 5, 9126 (2015).
[Crossref]

Other (2)

See the supplementary material and Refs. [31,32,36] for a detailed description of the experimental setup, the theory of SFWM biphoton generation from cold atoms, and the derivation of quantum beating and CHSH Bell parameter from frequency-bin entanglement, the heralded single-photon quantum state, and the biphoton waveform likeness between the two SFWM paths.

J. S. Bell, Speakable and Unspeakable in Quantum Mechanics (Cambridge University, 2004).

Supplementary Material (1)

NameDescription
» Supplement 1: PDF (1394 KB)      Supplementary material

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. Generation of frequency-bin entangled narrowband biphotons. (a) Experimental schematics of generating biphotons with double-path SFWM in cold Rb 85 atoms. Backward and paired Stokes ( ω s ) and anti-Stokes ( ω a s ) photons are spontaneously produced into paths 1 and 2, respectively, which are symmetric with angles of ± 3 ° to the longitudinal axis. The Stokes photons on path 1 go through FPS ( δ , Δ ϕ s ), while the anti-Stokes photons on path 2 go through FPS ( δ , Δ ϕ a s ). BS 1 and BS 2 are two beam splitters. D s ± and D a s ± are single-photon counting modules. (b)  Rb 85 atomic energy level diagram for SFWM. The atomic hyperfine levels are chosen as | 1 = | 5 S 1 / 2 , F = 2 , | 2 = | 5 S 1 / 2 , F = 3 , | 3 = | 5 P 1 / 2 , F = 3 , and | 4 = | 5 P 3 / 2 , F = 3 . The circularly polarized ( σ ) pump laser (780 nm) is blue-detuned by 60 MHz from the transition | 1 | 4 , whereas the coupling laser ( σ + , 795 nm) is on resonance to the transition | 2 | 3 . Panels (c) and (d) show the biphoton temporal correlations on paths 1 and 2, respectively. (e) Biphoton quantum beating measured between detectors D s + and D a s + and its visibility with the phase setting Δ ϕ s = 3 π / 2 and Δ ϕ a s = π / 4 . The solid curves in panels (c)–(e) are obtained from the SFWM biphoton theory [35].
Fig. 2.
Fig. 2. CHSH Bell inequality of frequency-bin entanglement. (a)  S as a function of a two-photon relative time delay of τ . The circles are experimental data. The solid curve is predicted by the theory. The dashed envelopes are plotted from ± 2 2 V ( τ ) , where the visibility V ( τ ) is determined by Eq. (4). The shadow area is the classical regime where | S | 2 . Panels (b)–(e) show the measured Bell correlations. The phase settings are Δ ϕ s = 0 , Δ ϕ a s = π / 4 , Δ ϕ s = π / 2 , and Δ ϕ a s = π / 4 .
Fig. 3.
Fig. 3. Two-photon nonlocal phase correlation. (a) Measured biphoton temporal correlations with different phase settings. (b) Phase correlations at τ = 252 ns . The error bars are standard deviations resulting from the statistical uncertainties of coincidence counts. The solid lines are the best fitting curves, with visibilities of V 1 = 0.86 ± 0.09 for Δ ϕ a s = π / 4 and V 2 = 0.85 ± 0.13 for Δ ϕ a s = π / 4 .
Fig. 4.
Fig. 4. Biphoton temporal beating. (a) Measured two-photon temporal correlations with different phase settings. The blue data are measured with Δ ϕ s = 3 π / 2 , Δ ϕ a s = π / 4 and the red data with Δ ϕ s = π , Δ ϕ a s = π / 4 . (b) Normalized beating signals. The solid curves are the best fittings.

Equations (9)

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

| Ψ X Y = 1 2 [ | ω s + δ | ω a s + X Y e i ( Δ ϕ a s Δ ϕ s ) | ω s | ω a s + δ ] ,
G X Y ( 2 ) ( τ ; Δ ϕ s , Δ ϕ a s ) = 1 2 [ G 0 ( 2 ) ( τ ) N 0 ] × [ 1 + X Y cos ( δ τ + Δ ϕ s Δ ϕ a s ) ] + N 0 ,
g X Y ( 2 ) ( τ ; Δ ϕ s , Δ ϕ a s ) = G X Y ( 2 ) ( τ ; Δ ϕ s , Δ ϕ a s ) / N 0 = 1 2 [ g 0 ( 2 ) ( τ ) 1 ] [ 1 + X Y cos ( δ τ + Δ ϕ s Δ ϕ a s ) ] + 1 ,
V ( τ ) = G 0 ( 2 ) ( τ ) N 0 G 0 ( 2 ) ( τ ) + N 0 = g 0 ( 2 ) ( τ ) 1 g 0 ( 2 ) ( τ ) + 1 .
C X Y ( τ ; Δ ϕ s , Δ ϕ a s ) = G X Y ( 2 ) ( τ ; Δ ϕ s , Δ ϕ a s ) η ξ Δ t bin T ,
E ( τ ; Δ ϕ s , Δ ϕ a s ) = C ++ + C C + C + C ++ + C + C + + C + .
E ( τ ; Δ ϕ s , Δ ϕ a s ) = C ++ ( τ ; Δ ϕ s , Δ ϕ a s ) C ++ ( τ ; Δ ϕ s , Δ ϕ a s ) C ++ ( τ ; Δ ϕ s , Δ ϕ a s ) + C ++ ( τ ; Δ ϕ s , Δ ϕ a s ) ,
S ( τ ) = E ( τ ; Δ ϕ s , Δ ϕ a s ) E ( τ ; Δ ϕ s , Δ ϕ a s ) + E ( τ ; Δ ϕ s , Δ ϕ a s ) + E ( τ ; Δ ϕ s , Δ ϕ a s ) .
S ( τ ) = 2 2 V ( τ ) cos ( δ τ + Δ ϕ s Δ ϕ a s + π 4 ) .

Metrics