Ultracold atom superfluidity induced by the Feshbach resonance

TL;DR

This paper explores how Feshbach resonances induce superfluidity in ultracold fermionic gases, highlighting signatures like gapped spectra and collective modes, and discusses experimental detection methods.

Contribution

It provides a detailed analysis of superfluid signatures near the phase transition and proposes experimental ways to detect the Goldstone mode.

Findings

Emergence of a gapped single-particle spectrum.

Presence of a collective Goldstone mode.

Manifestation of superfluid signatures near Tc.

Abstract

We discuss the possible signatures of superfluidity induced by the Feshbach resonance in ultracold gas of fermion atoms. Approaching the phase transition from above there appear various manifestations of the gradually emerging order parameter, but yet the long range coherence is not established due to strong quantum fluctuations. The single particle excitation spectrum becomes gapped while at the same time the pair excitations are characterized by the narrow quasiparticle peak surrounded by the incoherent background. This quasiparticle shows up certain collective features such as the remnant of the "first sound" which at Tc spreads down to low momenta. Presence of this Goldstone mode is the most unambiguous proof for appearance of the superfluid state. We discuss how such mode can be detected experimentally.