Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Sub-poissonian loading of single atoms in a microscopic dipole trap


The ability to manipulate individual atoms, ions or photons allows controlled engineering of the quantum state of small sets of trapped particles; this is necessary to encode and process information at the quantum level. Recent achievements in this direction have used either trapped ions1,2,3 or trapped photons in cavity quantum-electrodynamical systems3,4. A third possibility that has been studied theoretically5,6 is to use trapped neutral atoms. Such schemes would benefit greatly from the ability to trap and address individual atoms with high spatial resolution. Here we demonstrate a method for loading and detecting individual atoms in an optical dipole trap of submicrometre size. Because of the extremely small trapping volume, only one atom can be loaded at a time, so that the statistics of the number of atoms in the trap, N, are strongly sub-poissonian (ΔN2 ≈ 0.5N). We present a simple model for describing the observed behaviour, and we discuss the possibilities for trapping and addressing several atoms in separate traps, for applications in quantum information processing.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Main features of the experimental set-up.
Figure 2: Single atom detection.
Figure 3: Sub-poissonian loading.
Figure 4: Intensity autocorrelations g(t) of the MOT light emitted by the trapped atom (normalized for g(0) = 2 and g(∞) = 1).


  1. 1

    Sackett, C. A. et al. Experimental entanglement of four particles. Nature 404, 256–259 (2000).

    ADS  CAS  Article  Google Scholar 

  2. 2

    Steane, A. et al. Speed of ion-trap quantum-information processors. Phys. Rev. A 62, 042305-1–042305-9 (2000).

    ADS  Article  Google Scholar 

  3. 3

    Walther, H. Single atom experiments in cavities and trap. Proc. R. Soc. Lond. A 454, 431–445 (1998).

    ADS  CAS  Article  Google Scholar 

  4. 4

    Rauschenbeutel, A. et al. Coherent operation of a tunable quantum phase gate in cavity QED. Phys. Rev. Lett. 83, 5166–5169 (1999).

    ADS  CAS  Article  Google Scholar 

  5. 5

    Calarco, T., Briegel, H. J., Jaksch, D., Cirac, J. I. & Zoller, P. Entangling neutral atoms for quantum information processing. J. Mod. Opt. 47, 2137–2149 (2000).

    ADS  MathSciNet  CAS  Article  Google Scholar 

  6. 6

    Brennen, G. K., Deutsch, I. H. & Jessen, P. S. Entangling dipole-dipole interactions for quantum logic with neutral atoms. Phys. Rev. A 61, 062309-1–062309-10 (2000).

    ADS  MathSciNet  Article  Google Scholar 

  7. 7

    Morinaga, M., Bouchoule, I., Karam, J. C. & Salomon, C. Manipulation of motional quantum states of neutral atoms. Phys. Rev. Lett. 83, 4037–4040 (1999).

    ADS  CAS  Article  Google Scholar 

  8. 8

    Doherty, A. C., Lynn, T. W., Hood, C. J. & Kimble, H. J. Trapping of single atoms with single photons in cavity QED. Phys. Rev. A 63, 013401-1–013401-24 (2001).

    ADS  Article  Google Scholar 

  9. 9

    Pinkse, P. W. H., Fischer, T., Maunz, P. & Rempe, G. Trapping an atom with single photons. Nature 404, 365–368 (2000).

    ADS  CAS  Article  Google Scholar 

  10. 10

    Hu, Z. & Kimble, H. J. Observation of a single atom in a magneto-optical trap. Opt. Lett. 19, 1888–1890 (1994).

    ADS  CAS  Article  Google Scholar 

  11. 11

    Ruschewitz, F., Bettermann, D., Peng, J. L. & Ertmer, W. Statistical investigations on single trapped neutral atoms. Europhys. Lett. 34, 651–656 (1996).

    ADS  CAS  Article  Google Scholar 

  12. 12

    Frese, D. et al. Single atoms in an optical dipole trap: towards a deterministic source of cold atoms. Phys. Rev. Lett. 85, 3777–3780 (2000).

    ADS  CAS  Article  Google Scholar 

  13. 13

    Calarco, T. et al. Quantum gates with neutral atoms: Controlling collisional interactions in time-dependent traps. Phys. Rev. A 61, 022304-1–022304-11 (2000).

    ADS  Article  Google Scholar 

  14. 14

    Brennen, G. K., Caves, C. M., Jessen, P. S. & Deutsch, I. H. Quantum logic gates in optical lattices. Phys. Rev. Lett. 82, 1060–1063 (1999).

    ADS  CAS  Article  Google Scholar 

  15. 15

    DePue, M. T. et al. Unity occupation of sites in a 3D optical lattice. Phys. Rev. Lett. 82, 2262–2265 (1999).

    ADS  CAS  Article  Google Scholar 

  16. 16

    Rempe, G. & Walther, H. Sub-Poissonian atomic statistics in a micromaser. Phys. Rev. A 42, 1650–1655 (1990).

    ADS  CAS  Article  Google Scholar 

  17. 17

    Orzel, C., Tuchman, A. K., Fenselau, M. L., Yasuda, M. & Kasevich, M. A. Squeezed states in a Bose-Einstein condensate. Science 291, 2386–2389 (2001).

    ADS  CAS  Article  Google Scholar 

  18. 18

    Gensemer, S. D., Gould, P. L., Leo, P. J., Tiesinga, E. & Williams, C. J. Ultracold 87Rb ground-state hyperfine-changing collisions in the presence and absence of laser light. Phys. Rev. A 62, 030702-1–030702-4 (2000).

    ADS  Article  Google Scholar 

  19. 19

    Nesnidal, R. C. & Walker, T. G. Light-induced ultracold spin-exchange collisions. Phys. Rev. A 62, 030701-1–030701-4 (2000).

    ADS  Article  Google Scholar 

  20. 20

    Kuppens, S. J. M., Corwin, K. L., Miller, K. W., Chupp, T. E. & Wieman, C. E. Loading an optical dipole trap. Phys. Rev. A 62, 013406-1–013406-13 (2000).

    ADS  Article  Google Scholar 

  21. 21

    Jaksch, D. et al. Fast quantum gates for neutral atoms. Phys. Rev. Lett. 85, 2208–2211 (2000).

    ADS  CAS  Article  Google Scholar 

  22. 22

    Miller, J. D., Cline, R. A. & Heinzen, D. J. Far-off-resonance optical trapping of atoms. Phys. Rev. A 47, R4567–R4570 (1993).

    ADS  CAS  Article  Google Scholar 

Download references


The contributions of K. Vigneron, H. Wilhelm and T. Zhang to early stages of the experiment are acknowledged. This work was supported by the European IST/FET programme ‘QUBITS’ and by the European IHP network ‘QUEST’.

Author information



Corresponding author

Correspondence to Philippe Grangier.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Schlosser, N., Reymond, G., Protsenko, I. et al. Sub-poissonian loading of single atoms in a microscopic dipole trap. Nature 411, 1024–1027 (2001).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing