Odd-frequency pairing in a binary mixture of bosonic and fermionic cold atoms

TL;DR

This paper investigates a novel odd-frequency s-wave superfluid phase in a boson-fermion cold atom mixture, which could have higher transition temperatures than conventional p-wave pairing, and discusses its experimental feasibility.

Contribution

It introduces the possibility of odd-frequency s-wave pairing in cold atom mixtures and analyzes conditions for its realization and higher critical temperatures.

Findings

Odd-frequency s-wave pairing can occur alongside p-wave pairing.

Superfluid transition temperature can be higher for odd-frequency pairing.

Conditions near phase separation favor odd-frequency pairing.

Abstract

We study fermionic superfluidity in a boson-single-species-fermion cold atom mixture. We argue that apart from the standard p-wave fermion pairing mediated by the phonon field of the boson gas, the system also exhibits s-wave pairing with the anomalous correlator being an odd function of time or frequency. We show that such a superfluid phase can have a much higher transition temperature than the p-wave and may exist for sufficiently strong couplings between fermions and bosons. These conditions for odd-frequency pairing are favorable close to the value of the coupling at which the mixture phase-separates. We evaluate the critical temperatures for this system and discuss the experimental realization of this superfluid in ultracold atomic gases.