QFS2016 Book of Abstracts

Abstracts

O5.2 Pseudogap phenomena near the BKT transition of a two-dimensional ultracold Fermi gas in the crossover region M. Matsumoto, R. Hanai, D. Inotani, Y. Ohashi Keio University, Faculty of Science and Technology, Department of Physics, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan We investigate a 2D Fermi gas near the Berezinskii-Kosterlitz-Thouless (BKT) transition. Within the framework of a self-consistent T-matrix approximation, we clarify how strong 2D pairing fluctuations cause pseudogap phenomena in the low temperature region where the BKT transition has recently been observed in a 6Li Fermi gas [Ries et al., PRL 114, 230401 (2015), and Murthy et al., PRL 115, 010401 (2015)]. We also discuss how these pairing fluctuations lead to bosonic characters of this system in this regime. Since the BKT transition has recently become a realistic hot topic in cold Fermi gas physics, our results would be useful for the understanding of this unconventional Fermi superfluid. O5.3 Towards high-temperature superfluidity of excitons in TMDC Berman Oleg(1,2), Kezerashvili Roman(1,2) 1) Physics Department, New York City College of Technology, The City University of New York, Brooklyn, NY 11201, USA 2) The Graduate School and University Center, The City University of New York, New York, NY 10016, USA Two-dimensional dipolar excitons, formed by electrons and holes, spatially separated in two parallel transition metal dichalcogenide (TMDC) atomically thin layers, form superfluid at temperatures below the critical one. The effective masses of A and B dipolar excitons, collective excitations spectrum, sound velocity and critical temperature Tc for superfluidity were obtained for various TMDC bilayers. Tc for two-component exciton system in a TMDC bilayer is about one order of magnitude higher than Tc for any one-component exciton system, because for a two-component system Tc depends on the reduced mass of A and B excitons, which is always smaller than the individual mass of A or B exciton.

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