Sub-Poissonian atom-number fluctuations using light-assisted collisions

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 numb...

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Bibliographic Details
Published in:Physical review. A, Atomic, molecular, and optical physics Atomic, molecular, and optical physics, 2012-03, Vol.85 (3), Article 035403
Main Authors: Sortais, Y. R. P., Fuhrmanek, A., Bourgain, R., Browaeys, A.
Format: Article
Language:English
Subjects:
Asymptotic properties
Cold atoms
Collisions
Fluctuation
Mathematical models
Reduction
Statistics
Steady state
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Summary: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 [Display omitted] 2, we measure a reduction factor (Fano factor) of 0.72 plus or minus 0.07, which differs from 1 by more than four 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 multiatom losses, leading 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 the steady state. We thus show that we have reached the ultimate level of reduction in number fluctuations in our system.
ISSN:1050-2947
1094-1622
DOI:10.1103/PhysRevA.85.035403