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Quantum fluctuations and collective oscillations of a Bose-Einstein condensate in a 2D optical lattice

G. Orso·C. Menotti·S. Stringari
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Abstract

We use Bogoliubov theory to calculate the beyond mean field correction to the equation of state of a weakly interacting Bose gas in the presence of a tight 2D optical lattice. We show that the lattice induces a characteristic 3D to 1D crossover in the behaviour of quantum fluctuations. Using the hydrodynamic theory of superfluids, we calculate the corresponding shift of the collective frequencies of a harmonically trapped gas. We find that this correction can be of the order of a few percent and hence easily measurable in current experiments. The behavior of the quantum depletion of the condensate is also discussed.

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G. Orso, C. Menotti, S. Stringari. 2006-07-14. Quantum fluctuations and collective oscillations of a Bose-Einstein condensate in a 2D optical lattice. https://doi.org/10.1103/physrevlett.97.190408

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