Local Photoemission Spectra and Effects of Spatial Inhomogeneity in the BCS-BEC Crossover Regime of a Trapped Ultracold Fermi Gas

Abstract

We theoretically investigate single particle excitations in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein-Condensation) crossover regime of an ultracold Fermi gas. Including strong pairing fluctuations within a $T$-matrix approximation, as well as effects of a harmonic trap potential in the local density approximation, we calculate the local photoemission spectrum in the normal state. Recently, JILA group has measured this quantity in a ${}^{40}$K Fermi gas, in order to examine homogeneous single-particle properties of this system. Comparing our results with this experiment, we show that, this attempt indeed succeeds under the JILA's experimental condition. However, we also find that the current local photoemission spectroscopy still has room for improvement, in order to examine the pseudogap phenomenon predicted in the BCS-BEC crossover region. Since ultracold Fermi gases are always in a trap, our results would be useful in applying this system to various homogeneous Fermi systems, as a quantum simulator.

21 pages, 9 figures

References in corpus (16)

• Many-Body Physics with Ultracold Gases
• Theory of ultracold Fermi gases
• Weakly bound dimers of fermionic atoms
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• The Equation of State of a Low-Temperature Fermi Gas with Tunable Interactions
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Homogeneous Atomic Fermi Gases
• BCS-BEC crossover at finite temperature in the broken-symmetry phase
• Measurement of the Homogeneous Contact of a Unitary Fermi gas
• Evolution of the Normal State of a Strongly Interacting Fermi Gas from a Pseudogap Phase to a Molecular Bose Gas
• Breakdown of Fermi liquid description for strongly interacting fermions
• Pseudo-gap pairing in ultracold Fermi atoms
• Pseudogap phenomena in ultracold atomic Fermi gases
• Popov approximation for composite bosons in the BCS-BEC crossover
• Direct observation of the Fermi surface in an ultracold atomic gas

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• Single-particle Excitations and Strong Coupling Effects in the BCS-BEC Crossover Regime of a Rare-Earth Fermi Gas with an Orbital Feshbach Resonance
• Single-Particle properties of a strongly-interacting Bose-Fermi mixture with mass and population imbalance
• Spin susceptibility and effects of a harmonic trap in the BCS-BEC crossover regime of an ultracold Fermi gas
• Nonequilibrium BCS-BEC crossover and unconventional FFLO superfluid in a strongly interacting driven-dissipative Fermi gas
• Pseudogap regime of a two-dimensional uniform Fermi gas
• Isothermal compressibility and effects of multi-body molecular interactions in a strongly interacting ultracold Fermi gas
• Effects of finite-range interactions on the one-electron spectral properties of TTF-TCNQ
• Spin-dipole mode in a trapped Fermi gas near unitarity
• Peaks and widths of radio-frequency spectra: An analysis of the phase diagram of ultra-cold Fermi gases