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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.

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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).


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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’.

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Correspondence to Philippe Grangier.

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

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