Abstract

Using forced radio-frequency evaporation, we have cooled cesium atoms prepared in the sublevel F = -mF = 3 and confined in a magnetic trap. At the end of the evaporation ramp, the sample contains ~ 7000 atoms at 80 nK, corresponding to a phase space density 3 × 10-2. A molecular dynamics approach, including the effect of gravity, gives a good account for the experimental data, assuming a scattering length larger than 300 Å.

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References

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  1. M. H. Anderson, J. R. Ensher, M. R. Matthews, C. E. Wieman, and E. A. Cornell, Science 269, 1989 (1995).
  2. C. C. Bradley, C. A. Sackett, and R. G. Hulet, Phys. Rev. Lett. 78, 985 (1997).
    [CrossRef]
  3. C. C. Bradley, C. A. Sackett, J. J. Tollet, and R. G. Hulet, Phys. Rev. Lett. 75, 1687 (1995).
    [CrossRef] [PubMed]
  4. K. B. Davis, M.-O. Mewes, M. R. Andrews, N. J. van Druten, D. S. Durfee, D. M. Kurn, and W. Ketterle, Phys. Rev. Lett. 75, 3969 (1995).
    [CrossRef] [PubMed]
  5. M. R. Andrews, C. G. Townsend, H.-J. Miesner, D. S. Durfee, D. M. Kurn, and W. Ketterle, Science 275, 737 (1997).
    [CrossRef]
  6. E. A. Burt, R. W. Ghrist, C. J. Myatt, M. J. Holland, E. A. Cornell, and C. E. Wieman, Phys. Rev. Lett. 79, 337 (1997).
    [CrossRef]
  7. J. Soeding, D. Guery-Odelin, P. Desbiolles, G. Ferrari, and J. Dalibard, accepted for publication in Phys. Rev. Lett.
  8. A. Steane, P. Szriftgiser, P. Desbiolles, and J. Dalibard, Phys. Rev. Lett. 74, 4972 (1995).
    [CrossRef] [PubMed]
  9. H. F. Hess, Bull. Am. Phys. Soc.[2] 30, 854 (1985).
  10. O. J. Luiten, M. W. Reynolds, and J. T. M. Walraven, Phys. Rev. A 53, 381 (1996).
    [CrossRef] [PubMed]
  11. E. L. Surkov, J. T. M. Walraven, and G. V. Shlyapnikov, Phys. Rev. A 53, 3403 (1996).
    [CrossRef] [PubMed]
  12. W. Ketterle and N. J. van Druten, Adv. At. Mol. Opt. Phys. 37, 181 (1996).
    [CrossRef]
  13. H. Wu and C. Foot, J. Phys. B, 29, L321-L328 (1996).
    [CrossRef]
  14. L. D. Landau and E. M. Lifshitz, Quantum Mechanics (Pergamon Press, Oxford, 1977), Sect. 143.
  15. C. J. Joachain, Quantum collision theory, (North-Holland, Amsterdam, 1983) pp. 78-105
  16. M. Arndt, M. Ben Dahan, D. Guery-Odelin, M. W. Reynolds, and J. Dalibard, Phys. Rev. Lett. 79, 625 (1997).
    [CrossRef]
  17. A. Fioretti, D. Comparat, A. Crubellier, O. Dulieu, F. Masnou-Seeuws, and P. Pillet, preprint (November 1997).
  18. A. Kastberg, W. D. Phillips, S. L. Rolston, and R. J. C. Spreeuw, Phys. Rev. Lett. 74, 1542 (1995).
    [CrossRef] [PubMed]
  19. D. Boiron, A. Michaud, P. Lemonde, Y. Castin, C. Salomon, S. Weyers, K. Szymaniec, L. Cognet, and A. Clairon, Phys. Rev. A 53, R3734 (1996).
    [CrossRef] [PubMed]

Other

M. H. Anderson, J. R. Ensher, M. R. Matthews, C. E. Wieman, and E. A. Cornell, Science 269, 1989 (1995).

C. C. Bradley, C. A. Sackett, and R. G. Hulet, Phys. Rev. Lett. 78, 985 (1997).
[CrossRef]

C. C. Bradley, C. A. Sackett, J. J. Tollet, and R. G. Hulet, Phys. Rev. Lett. 75, 1687 (1995).
[CrossRef] [PubMed]

K. B. Davis, M.-O. Mewes, M. R. Andrews, N. J. van Druten, D. S. Durfee, D. M. Kurn, and W. Ketterle, Phys. Rev. Lett. 75, 3969 (1995).
[CrossRef] [PubMed]

M. R. Andrews, C. G. Townsend, H.-J. Miesner, D. S. Durfee, D. M. Kurn, and W. Ketterle, Science 275, 737 (1997).
[CrossRef]

E. A. Burt, R. W. Ghrist, C. J. Myatt, M. J. Holland, E. A. Cornell, and C. E. Wieman, Phys. Rev. Lett. 79, 337 (1997).
[CrossRef]

J. Soeding, D. Guery-Odelin, P. Desbiolles, G. Ferrari, and J. Dalibard, accepted for publication in Phys. Rev. Lett.

A. Steane, P. Szriftgiser, P. Desbiolles, and J. Dalibard, Phys. Rev. Lett. 74, 4972 (1995).
[CrossRef] [PubMed]

H. F. Hess, Bull. Am. Phys. Soc.[2] 30, 854 (1985).

O. J. Luiten, M. W. Reynolds, and J. T. M. Walraven, Phys. Rev. A 53, 381 (1996).
[CrossRef] [PubMed]

E. L. Surkov, J. T. M. Walraven, and G. V. Shlyapnikov, Phys. Rev. A 53, 3403 (1996).
[CrossRef] [PubMed]

W. Ketterle and N. J. van Druten, Adv. At. Mol. Opt. Phys. 37, 181 (1996).
[CrossRef]

H. Wu and C. Foot, J. Phys. B, 29, L321-L328 (1996).
[CrossRef]

L. D. Landau and E. M. Lifshitz, Quantum Mechanics (Pergamon Press, Oxford, 1977), Sect. 143.

C. J. Joachain, Quantum collision theory, (North-Holland, Amsterdam, 1983) pp. 78-105

M. Arndt, M. Ben Dahan, D. Guery-Odelin, M. W. Reynolds, and J. Dalibard, Phys. Rev. Lett. 79, 625 (1997).
[CrossRef]

A. Fioretti, D. Comparat, A. Crubellier, O. Dulieu, F. Masnou-Seeuws, and P. Pillet, preprint (November 1997).

A. Kastberg, W. D. Phillips, S. L. Rolston, and R. J. C. Spreeuw, Phys. Rev. Lett. 74, 1542 (1995).
[CrossRef] [PubMed]

D. Boiron, A. Michaud, P. Lemonde, Y. Castin, C. Salomon, S. Weyers, K. Szymaniec, L. Cognet, and A. Clairon, Phys. Rev. A 53, R3734 (1996).
[CrossRef] [PubMed]

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Figures (5)

Figure 1.
Figure 1.

(a) Three-coil configuration for the magnetic trap. The two opposite coils are also used for the MOT. (b) Two extra Helmholtz coils are used to compress the atomic cloud in the xz plane.

Figure 2.
Figure 2.

Time of flight analysis: the atoms are released from the magnetic trap at time τ = 0. We deduce the temperature from the vertical expansion of the cloud.

Figure 3.
Figure 3.

Evolution of (a) the number of atoms and (b) the temperature during the 10 last seconds of the evaporation ramp. Experimental data: ☐, numerical simulation: continuous line (|a| = 1000 Å), dashed line (|a| = 100 Å).

Figure 4.
Figure 4.

Series of pictures taken t seconds after the start of a 30 seconds linear evaporation ramp.

Figure 5.
Figure 5.

Evolution of the atomic phase space density during the 10 last seconds of the evaporation ramp. Experimental data: ☐, numerical simulation: continuous line (|a| = 1000 Å), dashed line (|a| = 100 Å).

Tables (1)

Tables Icon

Table 1. Predictions of the numerical simulation for the result of the evaporation, for various scattering lengths.

Equations (5)

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W ( z ) = 3 μ 4 B 0 2 + b 2 z 2 + mgz
z 0 = ( ( 1 ) 1 2 ) B 0 b ,
μ 4 B 0 2 + b 2 z 2 =
B 0 = 4 h ν 0 μ ( 1 2 ) 1 2
σ ( k ) = 8 π a 2 1 + k 2 a 2 ,

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