Coexistence of superfluid gap and pseudogap in the BCS-BEC crossover regime of a trapped Fermi gas below $T_{\mathrm{c}}$

Abstract

We investigate strong pairing fluctuations and effects of a harmonic trap in the superfluid phase of an ultracold Fermi gas. Including amplitude and phase fluctuations of the inhomogeneous superfluid order parameter $\Delta (r)$ in a trap within a combined $T$-matrix theory with the local density approximation, we examine local properties of single-particle excitations and a thermodynamic quantity in the BCS-BEC crossover region. Below the superfluid phase transition temperature $T_{\mathrm{c}}$, we show that inhomogeneous pairing fluctuations lead to a shell structure of the gas cloud in which the spatial region where the ordinary BCS-type superfluid density of states appears is surrounded by the region where the pseudogap associated with strong pairing fluctuations dominates single-particle excitations. The former spatial region enlarges to eventually cover the whole gas cloud far below $T_{\mathrm{c}}$. We also examine how this shell structure affects the photoemission spectrum, as well as the local pressure. Since a cold Fermi gas is always trapped in a harmonic potential, our results would be useful for the study of strong-coupling superfluid physics, including this realistic situation.

28 pages, 14 figures

References in corpus (10)

• Many-Body Physics with Ultracold Gases
• Theory of ultracold Fermi gases
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• Thermodynamics of the BCS-BEC crossover
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Measurement of the Entropy and Critical Temperature of a Strongly Interacting Fermi Gas
• BCS-BEC crossover at finite temperature in the broken-symmetry phase
• Pseudo-gap pairing in ultracold Fermi atoms
• Thermodynamics of a trapped unitary Fermi gas

Cited by in corpus (11)

• Uniform spin susceptibility and spin-gap phenomenon in the BCS-BEC crossover regime of an ultracold Fermi gas
• Strong-coupling corrections to ground-state properties of a superfluid Fermi gas
• Low-dimensional pairing fluctuations and pseudogapped photoemission spectrum in a trapped two-dimensional Fermi gas
• Strong-coupling corrections to spin susceptibility in the BCS-BEC crossover regime of a superfluid Fermi gas
• Local Photoemission Spectra and Effects of Spatial Inhomogeneity in the BCS-BEC Crossover Regime of a Trapped Ultracold Fermi Gas
• Hetero pairing and component-dependent pseudogap phenomena in an ultracold Fermi gas with mass imbalance
• Pseudogap phenomenon and effects of population imbalance in the normal state of a unitary Fermi gas
• Triplet pair amplitude in a trapped $s$-wave superfluid Fermi gas with broken spin rotation symmetry. II. Three dimensional continuum case
• Investigating Dirty Crossover through Fidelity Susceptibility and Density of States
• Spin Susceptibility and Strong Coupling Effects in an Ultracold Fermi Gas
• Spin susceptibility and effects of inhomogeneous strong pairing fluctuations in a trapped ultracold Fermi gas