Non-equilibrium strong-coupling theory for a driven-dissipative ultracold Fermi gas in the BCS-BEC crossover region

Abstract

We theoretically investigate strong-coupling properties of an ultracold Fermi gas in the BCS-BEC crossover regime in the non-equilibrium steady state, being coupled with two fermion baths. By developing a non-equilibrium strong-coupling theory based on the combined $T$-matrix approximation with the Keldysh Green's function technique, we show that the chemical potential bias applied by the two baths gives rise to the anomalous enhancement of Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) type pairing fluctuations (although the system has no spin imbalance), resulting in the re-entrant behavior of the non-equilibrium superfluid phase transition in the BCS-unitary regime. These pairing fluctuations are also found to anomalously enhance the pseudogap phenomenon. Since various non-equilibrium phenomena have recently been measured in ultracold Fermi gases, our non-equilibrium strong-coupling theory would be useful to catch up this experimental development in this research field.

21pages,15figures

References in corpus (19)

• Many-Body Physics with Ultracold Gases
• Quantum fluids of light
• Theory of ultracold Fermi gases
• An Open-System Quantum Simulator with Trapped Ions
• Quantum trajectories and open many-body quantum systems
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• Fulde-Ferrell-Larkin-Ovchinnikov State in Heavy Fermion Superconductors
• Spontaneous rotating vortex lattices in a pumped decaying condensate
• Non-equilibrium quantum condensation in an incoherently pumped dissipative system
• Observation of Quantized Conductance in Neutral Matter
• Ultra-cold Polarized Fermi Gases
• Two-terminal transport measurements with cold atoms
• Mean field phase diagrams of imbalanced Fermi gases near a Feshbach resonance
• Breakdown of Fermi liquid description for strongly interacting fermions
• Transition to a Bose-Einstein condensate of excitons at sub-Kelvin temperatures
• Broken translational and time-reversal symmetry in superconducting films
• Polarized Fermi gases at finite temperature in the BCS-BEC crossover
• A novel route to a finite center-of-mass momentum pairing state; current driven FFLO state