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.

arXiv comment5 pages, 2 figures, Proceedings of LT27

References in corpus (19)

• Many-Body Physics with 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
• Berezinskii-Kosterlitz-Thouless Crossover in a Trapped Atomic Gas
• Evidence for Superfluidity in a Resonantly Interacting Fermi Gas
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Resonantly-paired fermionic superfluids
• Observation of a pairing pseudogap in a two-dimensional Fermi gas
• Radiofrequency spectroscopy of a strongly interacting two-dimensional Fermi gas
• Evolution of Fermion Pairing from Three to Two Dimensions
• Single-particle properties and pseudogap effects in the BCS-BEC crossover regime of an ultracold Fermi gas above Tc
• Probing the Spectral Function Using Momentum Resolved Radio Frequency Spectroscopy in Trapped Fermi Gases
• 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
• Superfluidity, Sound Velocity and Quasi Condensation in the 2D BCS-BEC Crossover
• Evolution from BCS to BKT superfluidity in one-dimensional optical lattices
• Low-dimensional pairing fluctuations and pseudogapped photoemission spectrum in a trapped two-dimensional Fermi gas
• Pairing and radio-frequency spectroscopy in two-dimensional Fermi gases

Cited by in corpus (5)

• Observation of pair condensation in the quasi-2D BEC-BCS crossover
• 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
• Momentum distribution of Cooper-pairs and strong-coupling effects in a two-dimensional Fermi gas near the Berezinskii-Kosterlitz-Thouless transition
• Precision thermodynamics of the strongly interacting Fermi gas in two dimensions