Stability of the superfluid state in a disordered 1D ultracold fermionic gas

TL;DR

This paper investigates how disorder affects superfluidity in a 1D ultracold fermionic gas, revealing an intermediate phase where pairing persists without global superfluid order, using DMRG simulations.

Contribution

It demonstrates the existence of a disorder-enhanced superfluid phase and identifies an intermediate pseudogap phase before the insulator transition in a 1D disordered Fermi gas.

Findings

Disorder can enhance superfluidity in certain parameter regimes.

A pseudogap phase with strong pairing but no long-range order exists.

Superfluidity breaks down before the system becomes an insulator.

Abstract

We study a 1D Fermi gas with attractive short range-interactions in a disordered potential by the density matrix renormalization group (DMRG) technique. This setting can be implemented experimentally by using cold atom techniques. We identify a region of parameters for which disorder enhances the superfluid state. As disorder is further increased, global superfluidity eventually breaks down. However this transition occurs before the transition to the insulator state takes place. This suggests the existence of an intermediate metallic `pseudogap' phase characterized by strong pairing but no quasi long-range order.