Low-dimensional pairing fluctuations and pseudogapped photoemission spectrum in a trapped two-dimensional Fermi gas

Abstract

We investigate strong-coupling properties of a trapped two-dimensional normal Fermi gas. Within the framework of a combined $T$-matrix theory with the local density approximation, we calculate the local density of states, as well as the photoemission spectrum, to see how two-dimensional pairing fluctuations affect these single-particle quantities. In the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover region, we show that the local density of states exhibits a dip structure in the trap center, which is more remarkable than the three-dimensional case. This pseudogap phenomenon is found to naturally lead to a double peak structure in the photoemission spectrum. The peak-to-peak energy of the spectrum at p=0 agrees well with the recent experiment on a two-dimensional 40K Fermi gas [M. Feld, et al., Nature 480, 75 (2011)]. Since pairing fluctuations are sensitive to the dimensionality of a system, our results would be useful for the study of many-body physics in the BCS-BEC crossover regime of a two-dimensional Fermi gas.

20 pages, 7figures, Phys. Rev. A (2013), in press

References in corpus (13)

• Many-Body Physics with Ultracold Gases
• Theory of ultracold Fermi gases
• Scanning tunneling spectroscopy of high-temperature superconductors
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Radiofrequency spectroscopy of a strongly interacting two-dimensional Fermi gas
• Pseudo-gap pairing in ultracold Fermi atoms
• Cooper pairing above the critical temperature in a unitary Fermi gas
• Berezinskii-Kosterlitz-Thouless transition in trapped quasi-two-dimensional Fermi gas near a Feshbach resonance
• Pseudogap and preformed pairs in the imbalanced Fermi gas in two dimensions
• Pairing and radio-frequency spectroscopy in two-dimensional Fermi gases
• Coexistence of superfluid gap and pseudogap in the BCS-BEC crossover regime of a trapped Fermi gas below $T_{\mathrm{c}}$

Cited by in corpus (26)

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• Pairing effects in the normal phase of a two-dimensional Fermi gas
• Pairing effects in the non-degenerate limit of the two-dimensional Fermi gas
• Uniform spin susceptibility and spin-gap phenomenon in the BCS-BEC crossover regime of an ultracold Fermi gas
• Superfluid density and critical velocity near the fermionic Berezinskii-Kosterlitz-Thouless transition
• Comparison of strong-coupling theories for a two-dimensional Fermi gas
• Visualizing the BEC-BCS crossover in the two-dimensional Fermi gas: pairing gaps and dynamical response functions from ab initio computations
• Strong-coupling corrections to spin susceptibility in the BCS-BEC crossover regime of a superfluid Fermi gas
• Dynamical structure factors of a two-dimensional Fermi superfluid within random phase approximation
• Hetero pairing and component-dependent pseudogap phenomena in an ultracold Fermi gas with mass imbalance
• Quasi-condensation in two-dimensional Fermi gases
• Collective modes of a two-dimensional Fermi gas at finite temperature
• Precision Many-Body Study of the Berezinskii-Kosterlitz-Thouless Transition and Temperature-Dependent Properties in the Two-Dimensional Fermi Gas
• Pseudogap phenomenon and effects of population imbalance in the normal state of a unitary Fermi gas
• Dimensional crossover in a strongly interacting ultracold atomic Fermi gas
• Evolution of Cooper pairs with zero-center-of-mass momentum and their first-order correlation function in a two-dimensional ultracold Fermi gas near the observed Berezinskii-Kosterlitz-Thouless transition
• Pseudogap regime of a strongly interacting two-dimensional Fermi gas with and without confinement-induced effect range of interactions
• Beyond Gaussian pair fluctuation theory for strongly interacting Fermi gases
• Pseudogap phenomena in a two-dimensional ultracold Fermi gas near the Berezinskii-Kosterlitz-Thouless transition
• Role of the confinement-induced effective range on the thermodynamics of a strongly correlated Fermi gas in two dimensions
• Low-Dimensional Fluctuations and Pseudogap in Gaudin-Yang Fermi Gases
• Pseudogap regime of a two-dimensional uniform Fermi gas
• Two-dimensional spin-imbalanced Fermi gases at non-zero temperature: Phase separation of a non-condensate
• Momentum distribution of Cooper-pairs and strong-coupling effects in a two-dimensional Fermi gas near the Berezinskii-Kosterlitz-Thouless transition
• Peaks and widths of radio-frequency spectra: An analysis of the phase diagram of ultra-cold Fermi gases
• Spin susceptibility and effects of inhomogeneous strong pairing fluctuations in a trapped ultracold Fermi gas