Superfluidity of a spin-imbalanced Fermi gas in a three-dimensional optical lattice

2013/06/19 by Rafael Mendoza, M. Fortes, Mauricio Fortes +2
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Cooper pair #Fermi gas #Fermion #Hubbard model #Lattice (music) #Optical lattice #Pairing #Physics #Physics of Superconductivity and Magnetism #Population #Quantum mechanics #Quantum, superfluid, helium dynamics #Random phase approximation #Superconductivity #Superfluidity #cond-mat.quant-gas

paper · pdf · doi:10.1103/physreva.88.033606

published as Phys. Rev. A 88, 033606 (2013) · 8 pages, 5 figures

arxiv created 2013/06/19 · openalex publication_date 2013/09/06 · arxiv updated 2013/10/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We study fermion pairing in a population-imbalanced mixture of ⁶Li atomic gas loaded in a three-dimensional lattice at very low temperatures. Using the number equation for each population, the gap equation, and the equation for the Helmholtz free energy, we determine the gap, chemical potentials, and pair-momentum as functions of polarization. These parameters define the stability regions for a Fulde-Ferrell-Larkin-Ovchinnikov phase, a phase separation region where Bardeen-Cooper-Schrieffer and normal phases coexist, a Sarma phase when the pair-momentum vanishes, and the transition to the normal phase when the gap disappears. The collective-mode energies are then calculated using a Bethe-Salpeter approach in the generalized random-phase approximation assuming that the system is well described by the single-band Hubbard model. An interesting result is that this fermionic gas has a superfluid phase revealed by rotonlike minima in the asymmetric collective-mode energy spectrum.

Citations

• Fulde-Ferrell-Larkin-Ovchinnikov pairing in one-dimensional optical lattices
• Finite-Temperature Phase Diagram of a Polarized Fermi Gas in an Optical Lattice
• Quantum phase diagram of fermion mixtures with population imbalance in one-dimensional optical lattices
• Many-body physics with ultracold gases
• Collective modes and the speed of sound in the Fulde-Ferrell-Larkin-Ovchinnikov state
• Imbalanced Feshbach-resonant Fermi gases
• Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
• Collective modes as a probe of imbalanced Fermi gases
• The Fulde–Ferrell–Larkin–Ovchinnikov phase in the presence of pair hopping interaction
• Oscillatory pairing amplitude and magnetic compressible-incompressible transitions in imbalanced fermionic superfluids in optical lattices of elongated tubes
• Crossover from Cooper pairs to composite bosons: A generalized RPA analysis of collective excitations
• Finite-temperature phase diagram of a spin-polarized ultracold Fermi gas in a highly elongated harmonic trap
• Fermion pairing with spin-density imbalance in an optical lattice