QFS 2016 Book of Abstracts

Abstracts

P4.26 Zero-temperature properties of a strongly-interacting superfluid Fermi gas in the BCS-BEC crossover region Hiroyuki Tajima(1), Pieter van Wyk(1), Ryo Hanai(1), Daichi Kagamihara(1), Daisuke Inotani(1), Munekazu Horikoshi(2,3), and Yoji Ohashi(1) (1) Keio University, Faculty of Science and Technology, Department of Physics, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, Japan. (2) The university of Tokyo, Institute for Photon Science and Technology, Graduate School of Science, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan. (3) The university of Tokyo, Photon Science Center, Graduate School of Engeneering. 2-11-16, Yayoi, Bunkyo-ku, Tokyo, Japan. We theoretically investigate physical properties and strong-coupling effects in the BCS-BEC crossover regime of a superfluid Fermi gas at T=0. Within the framework of an extended T-matrix approximation, we evaluate various quantities, such as the compressibility, chemical potential, sound velocity, as well as the Tan’s contact. The calculated compressibility and chemical potential are shown to agree well with the recent experiments on a 6 Li superfluid Fermi gas in the crossover region. We also discuss how superfluid fluctuations affect these quantities at T=0. Our results would be useful for the understanding of quantum many-body effects in a strongly interacting Fermi superfluid. P4.27 Single-particle properties of a strongly interacting Bose-Fermi mixture above the BEC phase transition temperature D. Kharga(1), D. Inotani(1), R. Hanai(1), Y. Ohashi(1) 1) Keio University, Faculty of Science and Technology, Department of Physics, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, JAPAN We theoretically investigate normal state properties of a Bose-Fermi mixture with a strong attractive interaction between Fermi and Bose atoms. We extend the ordinary T-matrix approximation (TMA) with respect to Bose-Fermi pairing fluctuations, to include the Hugenholtz-Pines’ relation for all Bose Green’s functions appearing in TMA self-energy diagrams. This extension is shown to be essentially important to correctly describe physical properties of the Bose-Fermi mixture, especially near the BEC instability. Using this improved TMA, we clarify how the formation of composite fermions affects Bose and Fermi single-particle excitation spectra, over the entire interaction strength.

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