Critical Rotational Frequency for Superfluid Fermionic Gases across a Feshbach Resonance

TL;DR

This paper introduces a method to determine the critical rotational frequencies for superfluidity in Fermi gases across Feshbach resonances, revealing robustness of pairing and Landau level phenomena.

Contribution

It provides a novel approach to calculate critical rotation frequencies and uncovers the sequence of Landau level appearances in superfluid Fermi gases.

Findings

Superfluidity persists beyond a critical scattering length near resonance.

Landau levels cause jumps in the critical frequency, especially in small systems.

A superfluid core exists below the ultimate critical frequency in trapped gases.

Abstract

We present a method to determine the critical rotational frequencies for superfluidity of both uniform and trapped Fermi gases across wide Feshbach resonance. It is found that as one approaches the resonance from the BCS side, beyond a critical scattering length, pairing is so robust that superfluidity cannot be destroyed by rotation. Moreover, the critical frequency has a sequence of jumps revealing the appearance of Landau levels, which are particularly prominent for systems up to a few thousand particles. For rotational frequency below an "ultimate" critical frequency, defined to be the lowest frequency at which the center of the cloud goes normal, a trapped gas has a superfluid core surrounded by a normal gas, as seen in recent experiments.