Pseudogap phenomena in a two-dimensional ultracold Fermi gas near the Berezinskii-Kosterlitz-Thouless transition

Abstract

We investigate single-particle excitations and strong-coupling effects in a two-dimensional Fermi gas. Including pairing fluctuations within a Gaussian fluctuation theory, we calculate the density of states $\rho (\omega )$ near the Berezinskii-Kosterlitz-Thouless (BKT) transition temperature $T_{\mathrm{BKT}}$. Near $T_{\mathrm{BKT}}$, we show that superfluid fluctuations induce a pseudogap in $\rho (\omega )$. The pseudogap structure is very similar to the BCS superfluid density of states, although the superfluid order parameter is absent in the present two-dimensional case. Since a two-dimensional ${}^{40}$K Fermi gas has recently been realized, our results would contribute to the understanding of single-particle properties near the BKT instability.

5 pages, 2 figures, Proceedings of LT27

References in corpus (8)

• Many-Body Physics with Ultracold Gases
• Theory of ultracold Fermi gases
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Resonantly-paired fermionic superfluids
• Radiofrequency spectroscopy of a strongly interacting two-dimensional Fermi gas
• The effect of population imbalance on the Berezinskii-Kosterlitz-Thouless phase transition in a superfluid Fermi gas
• Pseudogap and preformed pairs in the imbalanced Fermi gas in two dimensions
• Pairing and radio-frequency spectroscopy in two-dimensional Fermi gases

Cited by in corpus (2)

• Observation of pair condensation in the quasi-2D BEC-BCS crossover
• Precision thermodynamics of the strongly interacting Fermi gas in two dimensions