Abstract

We have demonstrated a new technique for detecting ultracold atoms. A balanced detection technique was used to reduce laser-induced detection noise in conjunction with modulation-transfer spectroscopy to distinguish cold atoms from a thermal cloud. Using this technique, we have achieved signal-to-noise ratios in excess of 2000:1.

© 2001 Optical Society of America

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  1. G. Santarelli, Ph. Laurent, P. Lemonde, and A. Clairon, Phys. Rev. Lett. 82, 4619 (1999).
    [CrossRef]
  2. A. Peters, K. Y. Chung, and S. Chu, Nature 400, 849 (1999).
    [CrossRef]
  3. M. J. Snadden, J. M. McGuirk, P. Bouyer, K. G. Haritos, and M. A. Kasevich, Phys. Rev. Lett. 81, 971 (1998).
    [CrossRef]
  4. D. Durfee, J. B. Fixler, G. T. Foster, T. L. Gustavson, A. Landragin, J. M. McGuirk, and M. A. Kasevich, in IEEE Position, Location Navigation Symposium (Institute of Electrical and Electronics Engineers, New York, 2000), p. 395.
  5. R. W. P. Drever, J. L. Hall, F. V. Kawalski, J. Hough, G. M. Ford, A. J. Munley, and H. Ward, Appl. Phys. B 31, 97 (1983).
    [CrossRef]
  6. J. S. Shirley, Opt. Lett. 7, 537 (1982).
    [CrossRef] [PubMed]
  7. J. J. Synder, R. K. Raj, D. Bloch, and M. Ducloy, Opt. Lett. 5, 163 (1980).
    [CrossRef]
  8. This apparatus consisted of two atomic fountain–based, light-pulse accelerometers which simultaneously measured differential accelerations with high sensitivity and accuracy.
  9. The modulation depth was not a critical parameter, nor was the detuning of the probe beam and pump carrier beam so long as they had the same detuning.
  10. We defined this SNR as the ratio between the peak-to-peak fringe amplitude divided by the rms deviations of the residuals of the least-squares fit.
  11. Because of laser-induced detection noise, we must correlate noise fluctuations in two simultaneously detected atom ensembles in separate vacuum chambers, as in our gradiometer apparatus, to achieve this large SNR without balancing. The use of a balanced mode eliminated the need for this correlation.
  12. The amplitude-noise rejection was 40  dB over the detector bandwidth (dc to 10  MHz), which was measured with AM light on the detector. Frequency-noise rejection was characterized in two ways. High-frequency noise was driven at 2.5  kHz with an AOM during the atom detection (0.27  ms here) in the balanced mode. We studied low frequencies, making dc changes to the pump and probe detuning together in the balanced mode and measuring how balanced the detection remained. These two measurements gave similar noise-rejection levels.

1999 (2)

G. Santarelli, Ph. Laurent, P. Lemonde, and A. Clairon, Phys. Rev. Lett. 82, 4619 (1999).
[CrossRef]

A. Peters, K. Y. Chung, and S. Chu, Nature 400, 849 (1999).
[CrossRef]

1998 (1)

M. J. Snadden, J. M. McGuirk, P. Bouyer, K. G. Haritos, and M. A. Kasevich, Phys. Rev. Lett. 81, 971 (1998).
[CrossRef]

1983 (1)

R. W. P. Drever, J. L. Hall, F. V. Kawalski, J. Hough, G. M. Ford, A. J. Munley, and H. Ward, Appl. Phys. B 31, 97 (1983).
[CrossRef]

1982 (1)

1980 (1)

Bloch, D.

Bouyer, P.

M. J. Snadden, J. M. McGuirk, P. Bouyer, K. G. Haritos, and M. A. Kasevich, Phys. Rev. Lett. 81, 971 (1998).
[CrossRef]

Chu, S.

A. Peters, K. Y. Chung, and S. Chu, Nature 400, 849 (1999).
[CrossRef]

Chung, K. Y.

A. Peters, K. Y. Chung, and S. Chu, Nature 400, 849 (1999).
[CrossRef]

Clairon, A.

G. Santarelli, Ph. Laurent, P. Lemonde, and A. Clairon, Phys. Rev. Lett. 82, 4619 (1999).
[CrossRef]

Drever, R. W. P.

R. W. P. Drever, J. L. Hall, F. V. Kawalski, J. Hough, G. M. Ford, A. J. Munley, and H. Ward, Appl. Phys. B 31, 97 (1983).
[CrossRef]

Ducloy, M.

Durfee, D.

D. Durfee, J. B. Fixler, G. T. Foster, T. L. Gustavson, A. Landragin, J. M. McGuirk, and M. A. Kasevich, in IEEE Position, Location Navigation Symposium (Institute of Electrical and Electronics Engineers, New York, 2000), p. 395.

Fixler, J. B.

D. Durfee, J. B. Fixler, G. T. Foster, T. L. Gustavson, A. Landragin, J. M. McGuirk, and M. A. Kasevich, in IEEE Position, Location Navigation Symposium (Institute of Electrical and Electronics Engineers, New York, 2000), p. 395.

Ford, G. M.

R. W. P. Drever, J. L. Hall, F. V. Kawalski, J. Hough, G. M. Ford, A. J. Munley, and H. Ward, Appl. Phys. B 31, 97 (1983).
[CrossRef]

Foster, G. T.

D. Durfee, J. B. Fixler, G. T. Foster, T. L. Gustavson, A. Landragin, J. M. McGuirk, and M. A. Kasevich, in IEEE Position, Location Navigation Symposium (Institute of Electrical and Electronics Engineers, New York, 2000), p. 395.

Gustavson, T. L.

D. Durfee, J. B. Fixler, G. T. Foster, T. L. Gustavson, A. Landragin, J. M. McGuirk, and M. A. Kasevich, in IEEE Position, Location Navigation Symposium (Institute of Electrical and Electronics Engineers, New York, 2000), p. 395.

Hall, J. L.

R. W. P. Drever, J. L. Hall, F. V. Kawalski, J. Hough, G. M. Ford, A. J. Munley, and H. Ward, Appl. Phys. B 31, 97 (1983).
[CrossRef]

Haritos, K. G.

M. J. Snadden, J. M. McGuirk, P. Bouyer, K. G. Haritos, and M. A. Kasevich, Phys. Rev. Lett. 81, 971 (1998).
[CrossRef]

Hough, J.

R. W. P. Drever, J. L. Hall, F. V. Kawalski, J. Hough, G. M. Ford, A. J. Munley, and H. Ward, Appl. Phys. B 31, 97 (1983).
[CrossRef]

Kasevich, M. A.

M. J. Snadden, J. M. McGuirk, P. Bouyer, K. G. Haritos, and M. A. Kasevich, Phys. Rev. Lett. 81, 971 (1998).
[CrossRef]

D. Durfee, J. B. Fixler, G. T. Foster, T. L. Gustavson, A. Landragin, J. M. McGuirk, and M. A. Kasevich, in IEEE Position, Location Navigation Symposium (Institute of Electrical and Electronics Engineers, New York, 2000), p. 395.

Kawalski, F. V.

R. W. P. Drever, J. L. Hall, F. V. Kawalski, J. Hough, G. M. Ford, A. J. Munley, and H. Ward, Appl. Phys. B 31, 97 (1983).
[CrossRef]

Landragin, A.

D. Durfee, J. B. Fixler, G. T. Foster, T. L. Gustavson, A. Landragin, J. M. McGuirk, and M. A. Kasevich, in IEEE Position, Location Navigation Symposium (Institute of Electrical and Electronics Engineers, New York, 2000), p. 395.

Laurent, Ph.

G. Santarelli, Ph. Laurent, P. Lemonde, and A. Clairon, Phys. Rev. Lett. 82, 4619 (1999).
[CrossRef]

Lemonde, P.

G. Santarelli, Ph. Laurent, P. Lemonde, and A. Clairon, Phys. Rev. Lett. 82, 4619 (1999).
[CrossRef]

McGuirk, J. M.

M. J. Snadden, J. M. McGuirk, P. Bouyer, K. G. Haritos, and M. A. Kasevich, Phys. Rev. Lett. 81, 971 (1998).
[CrossRef]

D. Durfee, J. B. Fixler, G. T. Foster, T. L. Gustavson, A. Landragin, J. M. McGuirk, and M. A. Kasevich, in IEEE Position, Location Navigation Symposium (Institute of Electrical and Electronics Engineers, New York, 2000), p. 395.

Munley, A. J.

R. W. P. Drever, J. L. Hall, F. V. Kawalski, J. Hough, G. M. Ford, A. J. Munley, and H. Ward, Appl. Phys. B 31, 97 (1983).
[CrossRef]

Peters, A.

A. Peters, K. Y. Chung, and S. Chu, Nature 400, 849 (1999).
[CrossRef]

Raj, R. K.

Santarelli, G.

G. Santarelli, Ph. Laurent, P. Lemonde, and A. Clairon, Phys. Rev. Lett. 82, 4619 (1999).
[CrossRef]

Shirley, J. S.

Snadden, M. J.

M. J. Snadden, J. M. McGuirk, P. Bouyer, K. G. Haritos, and M. A. Kasevich, Phys. Rev. Lett. 81, 971 (1998).
[CrossRef]

Synder, J. J.

Ward, H.

R. W. P. Drever, J. L. Hall, F. V. Kawalski, J. Hough, G. M. Ford, A. J. Munley, and H. Ward, Appl. Phys. B 31, 97 (1983).
[CrossRef]

Appl. Phys. B (1)

R. W. P. Drever, J. L. Hall, F. V. Kawalski, J. Hough, G. M. Ford, A. J. Munley, and H. Ward, Appl. Phys. B 31, 97 (1983).
[CrossRef]

Nature (1)

A. Peters, K. Y. Chung, and S. Chu, Nature 400, 849 (1999).
[CrossRef]

Opt. Lett. (2)

Phys. Rev. Lett. (2)

M. J. Snadden, J. M. McGuirk, P. Bouyer, K. G. Haritos, and M. A. Kasevich, Phys. Rev. Lett. 81, 971 (1998).
[CrossRef]

G. Santarelli, Ph. Laurent, P. Lemonde, and A. Clairon, Phys. Rev. Lett. 82, 4619 (1999).
[CrossRef]

Other (6)

D. Durfee, J. B. Fixler, G. T. Foster, T. L. Gustavson, A. Landragin, J. M. McGuirk, and M. A. Kasevich, in IEEE Position, Location Navigation Symposium (Institute of Electrical and Electronics Engineers, New York, 2000), p. 395.

This apparatus consisted of two atomic fountain–based, light-pulse accelerometers which simultaneously measured differential accelerations with high sensitivity and accuracy.

The modulation depth was not a critical parameter, nor was the detuning of the probe beam and pump carrier beam so long as they had the same detuning.

We defined this SNR as the ratio between the peak-to-peak fringe amplitude divided by the rms deviations of the residuals of the least-squares fit.

Because of laser-induced detection noise, we must correlate noise fluctuations in two simultaneously detected atom ensembles in separate vacuum chambers, as in our gradiometer apparatus, to achieve this large SNR without balancing. The use of a balanced mode eliminated the need for this correlation.

The amplitude-noise rejection was 40  dB over the detector bandwidth (dc to 10  MHz), which was measured with AM light on the detector. Frequency-noise rejection was characterized in two ways. High-frequency noise was driven at 2.5  kHz with an AOM during the atom detection (0.27  ms here) in the balanced mode. We studied low frequencies, making dc changes to the pump and probe detuning together in the balanced mode and measuring how balanced the detection remained. These two measurements gave similar noise-rejection levels.

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Figures (3)

Fig. 1
Fig. 1

Diagram of the detection apparatus with two parallel probe beams for balanced detection and orthogonal pump beam for modulation transfer. The probe beams were detected on a balanced detector, mixed down to dc with a local oscillator (LO), and integrated on a digital voltmeter (DVM). All cubes are polarizing beam splitters. λ/2, half-wave plate; λ/4, quarter-wave plate.

Fig. 2
Fig. 2

(a) Modulation-transfer signal size as a function of pump intensity and probe intensity with the pump configuration shown in Fig.  1. The two data curves were taken at the probe and pump powers that gave the optimal signal. (b) Typical frequency line shapes, where Δ is the pump detuning from the probe frequency. The three peaks come from the correspondence of the probe frequency with the pump carrier and two sidebands. As the detuning becomes positive, one sideband nears resonance, which resulted in excessive noise.

Fig. 3
Fig. 3

(a) Normalized Ramsey fringe showing 1000:1 SNR. The solid curve is a least-squares fit. The residuals are from the fit for the data before × and after normalization. (b) SNR detected in balanced mode for various atom numbers Nat by use of FM molasses beams as pump beams. The solid line represents the shot-noise limit of Nat1/2, in good agreement with the measured SNR’s.

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