Pressure profiles of nonuniform two-dimensional atomic Fermi gases

TL;DR

This study measures pressure profiles in 2D atomic Fermi gases with varying interactions, comparing experimental results to theoretical models and revealing insights into the effects of interactions and kinematics in these quantum systems.

Contribution

First measurement of pressure profiles in 2D atomic Fermi gases across different interaction regimes, with detailed comparison to multiple theoretical models.

Findings

Pressure above Landau Fermi-liquid theory in weak interactions

Pressure below Monte Carlo predictions in strong interactions

Kinematics remains effectively 2D even at strong interactions

Abstract

Spatial profiles of the pressure have been measured in atomic Fermi gases with primarily 2D kinematics. The in-plane motion of the particles is confined by a gaussian-shape potential. The two-component deeply-degenerate Fermi gases are prepared at different values of the s-wave attraction. The pressure profile is found using the force-balance equation, from the measured density profile and the trapping potential. The pressure is compared to zero-temperature models within the local density approximation. In the weakly-interacting regime, the pressure lies above a Landau Fermi-liquid theory and below the ideal-Fermi-gas model, whose prediction coincides with that of the Cooper-pair mean-field theory. The values closest to the data are provided by the approach where the mean-field of Cooper pairs is supplemented with fluctuations. In the regime of strong interactions, in response to the increasing attraction, the pressure shifts below this model reaching lower values calculated within Monte Carlo methods. Comparison to models shows that interaction-induced departure from 2D kinematics is either small or absent. In particular, comparison with a lattice Monte Carlo suggests that kinematics is 2D in the strongly-interacting regime.