BCS and BEC p-wave pairing in Bose-Fermi gases

TL;DR

This paper investigates p-wave superfluidity in Bose-Fermi mixtures, showing how attractive interactions induced by bosonic density fluctuations can lead to a transition from BCS superfluidity to tightly bound pairs forming a BEC.

Contribution

It provides a detailed analysis of p-wave pairing in Bose-Fermi gases without assuming a specific pairing field form, exploring the transition from BCS to BEC regimes.

Findings

Identification of conditions for p-wave superfluidity

Demonstration of BCS to BEC transition with interaction strength

No specific ansatz used for pairing or interaction

Abstract

The pairing of fermionic atoms in a mixture of atomic fermion and boson gases at zero temperature is investigated. The attractive interaction between fermions, that can be induced by density fluctuations of the bosonic background, can give rise to a superfluid phase in the Fermi component of the mixture. The atoms of both species are assumed to be in only one internal state, so that the pairing of fermions is effective only in odd-l channels. No assumption about the value of the ratio between the Fermi velocity and the sound velocity in the Bose gas is made in the derivation of the energy gap equation. The gap equation is solved without any particular "ansatz" for the pairing field or the effective interaction. The p-wave superfluidity is studied in detail. By increasing the strength and/or decreasing the range of the effective interaction a transition of the fermion pairing regime, from the Bardeen-Cooper-Schrieffer state to a system of tightly bound couples can be realized. These composite bosons behave as a weakly-interacting Bose-Einstein condensate.