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

27th International Conference on Low Temperature Physics

Matsumoto, M.^1 ; Ohashi, Y.^1

Department of Physics, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Kanagawa, Yokohama

223-8522, Japan^1

关键词: Berezinskii-Kosterlitz-Thouless transition;    Density of state;    Gaussian fluctuations;    Pairing fluctuations;    Single particle excitations;    Strong coupling;    Superfluid density;    Superfluid order parameter;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/568/1/012012/pdf
DOI  :  10.1088/1742-6596/568/1/012012

来源: IOP

【 摘 要 】

We investigate single-particle excitations and strong-coupling effects in a twodimensional Fermi gas. Including pairing fluctuations within a Gaussian fluctuation theory, we calculate the density of states ρ(ω) near the Berezinskii-Kosterlitz-Thouless (BKT) transition temperature TBKT. Near TBKT, we show that superfluid fluctuations induce a pseudogap in ρ(ω). 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 twodimensional40K Fermi gas has recently been realized, our results would contribute to the understanding of single-particle properties near the BKT instability.