Superfluid phase transition and strong-coupling effects in an ultracold Fermi gas with mass imbalance

Abstract

We investigate the superfluid phase transition and effects of mass imbalance in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover regime of an cold Fermi gas. We point out that the Gaussian fluctuation theory developed by Nozières and Schmitt-Rink and the $T$-matrix theory, that are now widely used to study strong-coupling physics of cold Fermi gases, give unphysical results in the presence of mass imbalance. To overcome this problem, we extend the $T$-matrix theory to include higher-order pairing fluctuations. Using this, we examine how the mass imbalance affects the superfluid phase transition. Since the mass imbalance is an important key in various Fermi superfluids, such as ${}^{40}$K-${}^6$Li Fermi gas mixture, exciton condensate, and color superconductivity in a dense quark matter, our results would be useful for the study of these recently developing superfluid systems.

7 pages, 4 figures, Proceedings of QFS-2012

References in corpus (6)

• Many-Body Physics with Ultracold Gases
• Theory of ultracold Fermi gases
• Quantum degenerate two-species Fermi-Fermi mixture coexisting with a Bose-Einstein condensate
• Transition to a Bose-Einstein condensate of excitons at sub-Kelvin temperatures
• BCS-BEC crossover in an asymmetric two-component Fermi gas
• Population and mass imbalance in atomic Fermi gases

Cited by in corpus (2)

• Beyond-mean-field description of a trapped unitary Fermi gas with mass and population imbalance
• Interplay of mass imbalance and frustration in correlated band insulators