Finite Temperature Momentum Distribution of a Trapped Fermi Gas

TL;DR

This paper reports experimental measurements of how the momentum distribution of a trapped Fermi gas varies with temperature across the BCS-BEC crossover, highlighting non-monotonic effects due to thermal broadening and gap reduction.

Contribution

It provides the first detailed comparison between experimental data and mean-field theoretical predictions for temperature-dependent momentum distributions in a Fermi gas.

Findings

Observation of non-monotonic temperature effects on momentum distribution.

Agreement between experimental results and mean-field theory.

Identification of the interplay between thermal broadening and gap narrowing.

Abstract

We present measurements of the temperature-dependent momentum distribution of a trapped Fermi gas consisting of $^{40}$K in the BCS-BEC crossover regime. Accompanying theoretical results based upon a simple mean-field ground state are compared to the experimental data. Non-monotonic effects associated with temperature, $T$, arise from the competition between thermal broadening and a narrowing of the distribution induced by the decrease in the excitation gap $\Delta(T)$ with increasing $T$.