Insulating Behavior of a Trapped Ideal Fermi Gas

TL;DR

This paper studies how an ideal Fermi gas transitions from conducting to insulating behavior in a combined lattice and harmonic trap, using both theoretical analysis and experiments, based on the Fermi energy's position relative to the bandgap.

Contribution

It provides a combined theoretical and experimental analysis of the insulating crossover in a trapped ideal Fermi gas within a lattice potential.

Findings

Crossover from conducting to insulating regime observed as Fermi energy enters the bandgap.

Oscillatory motion in the conducting regime; localized center of mass in the insulating regime.

Experimental verification of the theoretical predictions.

Abstract

We investigate theoretically and experimentally the center-of-mass motion of an ideal Fermi gas in a combined periodic and harmonic potential. We find a crossover from a conducting to an insulating regime as the Fermi energy moves from the first Bloch band into the bandgap of the lattice. The conducting regime is characterized by an oscillation of the cloud about the potential minimum, while in the insulating case the center of mass remains on one side of the potential.