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arXiv:cond-mat/0703169 · Physical Review Letters

Intrinsic Heating and Cooling in Adiabatic Processes for Bosons in Optical Lattices

Tin-Lun Ho, Qi Zhou

Published Sep 19, 2007• 72 citations
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Abstract

We show that by raising the lattice "adiabatically" as in many current optical lattice experiments on bosons, even though the temperature may decrease initially, it will eventually rise linearly with lattice height, taking the system farther away from quantum degeneracy. This increase has nothing to do with the entropy of the bulk Mott phase and is caused by the adiabatic compression of the mobile atoms between Mott layers. Our studies show that one can reverse the temperature rise to reach quantum degeneracy by adiabatic expansion, which can be achieved by a variety of methods.

DOI
10.1103/physrevlett.99.120404

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When atoms are loaded into an optical lattice, the process of gradually turning on the lattice is almost adiabatic. In this paper, we investigate how the temperature changes when going from the gapless superfluid phase to the gapped Mott phase along isentropic lines. To do so we calculate the entropy in the single-band Bose–Hubbard model for various densities, interaction strengths and temperatures in one and two dimensions for homogeneous and trapped systems. Our theory is able to reproduce the experimentally observed visibilities and therefore strongly supports the view that current experiments remain in the quantum regime for the considered lattice depths with low temperatures and minimal heating.
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