Condensate Fraction of a Fermi Gas in the BCS-BEC Crossover

TL;DR

This paper provides an explicit formula for the condensate density in a Fermi gas across the BCS-BEC crossover, analyzing the condensate fraction and comparing theoretical predictions with experimental data.

Contribution

It introduces a new explicit formula for the condensate density as a function of chemical potential and energy gap in the BCS-BEC crossover.

Findings

Theoretical results agree with experimental data on condensate behavior.

Condensate fraction behavior is characterized across the Feshbach resonance.

Provides insights into condensate properties at zero temperature.

Abstract

We investigate the Bose-Einstein condensation of Fermionic pairs in a uniform two-component Fermi gas obtaining an explicit formula for the condensate density as a function of the chemical potential and the energy gap. We analyze the condensate fraction in the crossover from the Bardeen-Cooper-Schrieffer (BCS) state of weakly-interacting Cooper pairs to the Bose-Einstein Condensate (BEC) of molecular dimers. By using the local density approximation we study confined Fermi vapors of alkali-metal atoms for which there is experimental evidence of condensation also on the BCS side of the Feshbach resonance. Our theoretical results are in agreement with these experimental data and give the behavior of the condensate on both sides of the Feshbach resonance at zero temperature.