Crossover from 2D to 3D in a weakly interacting Fermi gas

TL;DR

This paper investigates the transition from two to three dimensions in a weakly interacting Fermi gas, identifying the critical atom number where the gas shifts from 2D to quasi-2D behavior through experimental measurements.

Contribution

It provides experimental evidence of the dimensional crossover in a Fermi gas and characterizes the shell structure associated with transverse oscillator states.

Findings

Identification of the critical atom number $N_{2D}$ for 2D to 3D transition

Observation of shell structure in the quasi-2D regime

Measurement of cloud size and aspect ratio changes

Abstract

We have studied the transition from two to three dimensions in a low temperature weakly interacting $^6$Li Fermi gas. Below a critical atom number, $N_{2D}$, only the lowest transverse vibrational state of a highly anisotropic oblate trapping potential is occupied and the gas is two-dimensional. Above $N_{2D}$ the Fermi gas enters the quasi-2D regime where shell structure associated with the filling of individual transverse oscillator states is apparent. This dimensional crossover is demonstrated through measurements of the cloud size and aspect ratio versus atom number.