BCS-BEC crossover in spatially modulated fermionic condensates

TL;DR

This paper explores the phase structure and thermodynamics of multi-component fermionic condensates during the BCS-BEC crossover, highlighting the persistence of inhomogeneous phases like the Fulde-Ferrell state across different coupling regimes.

Contribution

It provides a detailed analysis of inhomogeneous superconducting phases, such as Fulde-Ferrell, across the BCS-BEC crossover, emphasizing their stability in various regimes.

Findings

Inhomogeneous phases persist through the crossover.

Fulde-Ferrell phase appears at low temperatures and high asymmetries.

Inhomogeneous phases may exist beyond the strong coupling transition.

Abstract

Several novel multi-component fermionic condensates show universal behavior under imbalance in the number of fermionic species. Here I discuss their phase structure, thermodynamics, and the transition from the weak (BCS) to strong (BEC) coupling regime. The inhomogeneous superconducting phases are illustrated on the example of the Fulde-Ferrell phase which appears in the weak coupling regime, at low temperatures and large asymmetries. The inhomogeneous phases persist through the crossover up to (and possibly beyond) the transition to the strong coupling regime.