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arXiv · 1111.5203

Sub-Poissonian atom number fluctuations using light-assisted collisions

Y. R. P. Sortais·A. Fuhrmanek·R. Bourgain·A. Browaeys
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Abstract

We investigate experimentally the number statistics of a mesoscopic ensemble of cold atoms in a microscopic dipole trap loaded from a magneto-optical trap, and find that the atom number fluctuations are reduced with respect to a Poisson distribution due to light-assisted two-body collisions. For numbers of atoms N>2, we measure a reduction factor (Fano factor) of 0.72+/-0.07, which differs from 1 by more than 4 standard deviations. We analyze this fact by a general stochastic model describing the competition between the loading of the trap from a reservoir of cold atoms and multi-atom losses, which leads to a master equation. Applied to our experimental regime, this model indicates an asymptotic value of 3/4 for the Fano factor at large N and in steady state. We thus show that we have reached the ultimate level of reduction in number fluctuations in our system.

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Y. R. P. Sortais, A. Fuhrmanek, R. Bourgain, A. Browaeys. 2012-01-23. Sub-Poissonian atom number fluctuations using light-assisted collisions. https://doi.org/10.1103/physreva.85.035403

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