Pairing gaps in atomic gases at the BCS-BEC crossover

TL;DR

This paper investigates pairing gaps and superfluidity in atomic Fermi gases across the BCS-BEC crossover, using semiclassical solutions to the Bogoliubov-deGennes equations to explain experimental observations.

Contribution

It provides a theoretical calculation of quasiparticle excitation energies at the crossover, linking them to experimental pairing gap measurements and collective mode damping.

Findings

Quasiparticle excitation energies set the scale for pairing gaps.

Damping of radial breathing mode occurs when quasiparticle energies match trap frequency.

Theoretical results align with experimental evidence of superfluidity.

Abstract

Strong evidence for pairing and superfluidity has recently been found in atomic Fermi gases at the BCS-BEC crossover both in collective modes and RF excitation energies. It is argued that the scale for the effective pairing gaps measured in RF experiments is set by the lowest quasiparticle in-gap excitation energies. These are calculated at the BCS-BEC crossover from semiclassical solutions to the Bogoliubov-deGennes equations. The strong damping of the radial breathing mode observed in the BCS limit occur when the lowest quasiparticle excitation energies coincide with the radial frequency, which indicates that a coupling between them take place.