Superfluid properties of an ultracold Fermi gas with an orbital Feshbach resonance in the BCS-BEC crossover region
arXiv:2103.16933 · doi:10.1103/PhysRevA.103.053319
Abstract
We theoretically investigate superfluid properties of a two-band gas of Yb Fermi atoms with an orbital Feshbach resonance (OFR). To describe the BCS-BEC crossover region, we include superfluid fluctuations caused by inter-band and intra-band pairing interactions associated with OFR, by extending the strong-coupling theory developed by Nozières and Schmitt-Rink to the two-band case below the superfluid phase transition temperature; however, effects of an experimentally inaccessible deep bound state are removed, to model a real Yb Fermi gas near OFR. We show that the condensate fraction in the upper closed channel gradually becomes smaller than that in the lower open channel, as one moves from the strong- to the weak-coupling regime, because the OFR-pairing mechanism tunes the interaction strengths by adjusting the energy difference between the two bands. However, even when the closed-channel band is much higher in energy than the open-channel band in the weak-coupling regime, the magnitude of the superfluid order parameter in the closed channel is found to be still comparable to that in the open channel. As the reason for this, we point out a pair-tunneling effect by the OFR-induced inter-band interaction. Besides these superfluid quantities, we also examine collective modes, such as the Goldstone mode, Schmid (Higgs) mode, as well as Leggett mode, to clarify how they appear in the spectral weights of pair-correlation functions in each band. Since the realization of a multi-band superfluid Fermi gas is a crucial issue in cold Fermi gas physics, our results would contribute to the basic understanding of this type of Fermi superfluid in the BCS-BEC crossover region.
arXiv comment31 pages, 10 figures
References in corpus (37)
- Many-Body Physics with Ultracold Gases
- Feshbach Resonances in Ultracold Gases
- Theory of ultracold Fermi gases
- Observation of resonance condensation of fermionic atom pairs
- Condensation of Pairs of Fermionic Atoms Near a Feshbach Resonance
- BCS-BEC Crossover: From High Temperature Superconductors to Ultracold Superfluids
- Evidence for Superfluidity in a Resonantly Interacting Fermi Gas
- Collective excitations of a degenerate gas at the BEC-BCS crossover
- Molecular Probe of Pairing in the BEC-BCS Crossover
- Amplitude / Higgs Modes in Condensed Matter Physics
- Thermodynamics of the BCS-BEC crossover
- Degenerate Fermi Gases of Ytterbium
- Quantum Fluctuations in the Superfluid State of the BCS-BEC Crossover
- Collective mode of homogeneous superfluid Fermi gases in the BEC-BCS crossover
- Observation of an orbital interaction-induced Feshbach resonance in 173-Yb
- Superfluidity and collective modes in a uniform gas of Fermi atoms with a Feshbach resonance
- A strongly interacting gas of two-electron fermions at an orbital Feshbach resonance
- Orbital Feshbach Resonance in Alkali-Earth Atoms
- Superfluid density and condensate fraction in the BCS-BEC crossover regime at finite temperatures
- Condensate Fraction of a Fermi Gas in the BCS-BEC Crossover
- Pair-Breaking Collective Branch in BCS Superconductors and Superfluid Fermi Gases
- Strongly correlated Fermi superfluid near an orbital Feshbach resonance: Stability, equation of state and Leggett mode
- Enhanced critical temperature, pairing fluctuation effects, and BCS-BEC crossover in a two-band Fermi gas
- Orbital Feshbach Resonance: A "Wide" Narrow Resonance for Higher Transition Temperature Fermi Superfluid
- Two-band superfluidity and intrinsic Josephson effect in alkaline-earth Fermi gases across an orbital Feshbach resonance
- Collective Modes in a Two-band Superfluid of Ultracold Alkaline-earth Atoms Close to an Orbital Feshbach Resonance
- The Higgs mode in a superfluid of Dirac fermions
- A strongly interacting Sarma superfluid near orbital Feshbach resonances
- Trapped Yb Fermi gas across an orbital Feshbach resonance
- Repulsive polarons in alkaline-earth(-like) atoms across an orbital Feshbach resonance
- Topological Fulde-Ferrell states in alkaline-earth-metal-like atoms near an orbital Feshbach resonance
- Bound State and Order Parameter Mixing Effect by Nonmagnetic Impurity Scattering in Two-band Superconductors
- Single-particle Excitations and Strong Coupling Effects in the BCS-BEC Crossover Regime of a Rare-Earth Fermi Gas with an Orbital Feshbach Resonance
- Orbital Feshbach Resonance with Small Energy Gap between Open and Closed Channels
- Leggett collective excitations in a two-band Fermi superfluid at finite temperatures
- Frustrated orbital Feshbach resonances in a Fermi gas
- Enhanced Fulde-Ferrell-Larkin-Ovchinnikov and Sarma superfluid states near an orbital Feshbach resonance