Cold asymmetrical fermion superfluids

Abstract

In this work we investigate the general properties and the ground state of an asymmetrical dilute gas of cold fermionic atoms, formed by two particle species having different densities. We have shown in a recent paper, that a mixed phase composed of normal and superfluid components is the energetically favored ground state of such a cold fermionic system. Here we extend the analysis and verify that in fact, the mixed phase is the preferred ground state of an asymmetrical superfluid in various situations. We predict that the mixed phase can serve as a way of detecting superfluidity and estimating the magnitude of the gap parameter in asymmetrical fermionic systems. *

Nesting and lifetime effects in the FFLO state of quasi-one-dimensional imbalanced Fermi gases

“…In three-dimensional (3D) systems, in the strongly-interacting limit, experiments show [3,4,5,6,7] that the gas phase separates with an unpolarized superfluid core surrounded by a polarized shell [13,14], with no evidence for the FFLO phase [7]. However, in one-dimensional (1D) imbalanced Fermi gases, the observed density profiles [8] agree quantitatively well with theories that exhibit the 1D equivalent of FFLO correlations at low temperatures [9,10,11,12].…”

Stability Criteria for Breached-Pair Superfluidity

“…In the context of two component fermionic systems as considered in [2,8,12], three competing homogeneous phases have been considered: a normal state of free fermions (N), a fully gapped superfluid phase (BCS), and a gapless BP phase. The BCS phase has complete pairing between the two species, and thus enforces equal densities.…”

Finite-temperature phase diagram of quasi-two-dimensional imbalanced Fermi gases beyond mean field

“…where [28,30,31], one sees that increasing the imbalance h and keeping µ fixed, the minimum is still located at ∆ 0 up to a maximum or critical imbalance h c , after which there is a quantum phase transition to the normal state with ∆ = 0. h c is found through the equality Ω 0 = Ω N imb , which yields…”