Interaction dependent temperature effects in Bose-Fermi mixtures in optical lattices

TL;DR

This paper provides a finite temperature analysis of Bose-Fermi mixtures in optical lattices, highlighting the importance of temperature effects and their dependence on inter-species interactions, and compares theoretical predictions with experimental results.

Contribution

It introduces a model accounting for interaction-dependent temperature effects during lattice ramp-up, improving understanding of coherence in Bose-Fermi mixtures.

Findings

The theory reproduces experimental coherence dependence on interactions.

Adiabatic temperature changes significantly affect system properties.

Discrepancies may be due to confinement-dependent scattering lengths.

Abstract

We present a quantitative finite temperature analysis of a recent experiment with Bose-Fermi mixtures in optical lattices, in which the dependence of the coherence of bosons on the inter-species interaction was analyzed. Our theory reproduces the characteristics of this dependence and suggests that intrinsic temperature effects play an important role in these systems. Namely, under the assumption that the ramping up of the optical lattice is an isentropic process, adiabatic temperature changes of the mixture occur that depend on the interaction between bosons and fermions. Matching the entropy of two regimes---no lattice on the one hand and deep lattices on the other---allows us to compute the temperature in the lattice and the visibility of the quasi-momentum distribution of the bosonic atoms, which we compare to the experiment. We briefly comment on the remaining discrepancy between theory and experiment, speculating that it may in part be attributed to the dependence of the Bose-Fermi scattering length on the confinement of the atoms.