Ground-state pressure of quasi-2D Fermi and Bose gases

TL;DR

This study experimentally measures the pressure and density of a quasi-2D ultracold atomic gas across various interaction regimes, providing data to test and refine theoretical models in low-dimensional quantum systems.

Contribution

It presents the first comprehensive experimental measurement of pressure in a quasi-2D Fermi and Bose gas across different interaction regimes, challenging existing theories and offering data for model validation.

Findings

Pressure exceeds Fermi-liquid predictions in weakly attractive Fermi gases.

Pressure aligns with bosonic mean-field scaling in the Bose regime.

Discrepancies observed with purely 2D models in strongly interacting regimes.

Abstract

Using an ultracold gas of atoms, we have realized a quasi-two-dimensional Fermi system with widely tunable s-wave interactions nearly in a ground state. Pressure and density are measured. The experiment covers physically different regimes: weakly and strongly attractive Fermi gases and a Bose gas of tightly bound pairs of fermions. In the Fermi regime of weak interactions, the pressure is systematically above a Fermi-liquid-theory prediction, maybe due to mesoscopic effects. In the opposite Bose regime, the pressure agrees with a bosonic mean-field scaling in a range beyond simplest expectations. In the strongly interacting regime, measurements disagree with a purely 2D model. Reported data may serve for sensitive testing of theoretical methods applicable across different quantum physics disciplines.