Pseudogap Phenomena Near the BKT Transition of a Two-Dimensional Ultracold Fermi Gas in the Crossover Region

M. Matsumoto, R. Hanai, Daisuke Inotani, Yoji Ohashi

Research output: Contribution to journalArticle

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Abstract

We investigate strong-coupling properties of a two-dimensional ultracold Fermi gas in the normal phase. In the three-dimensional case, it has been shown that the so-called pseudogap phenomena can be well described by a (non-self-consistent) T-matrix approximation (TMA). In the two-dimensional case, while this strong-coupling theory can explain the pseudogap phenomenon in the strong-coupling regime, it unphysically gives large pseudogap size in the crossover region, as well as in the weak-coupling regime. We show that this difficulty can be overcome when one improves TMA to include higher-order pairing fluctuations within the framework of a self-consistent T-matrix approximation (SCTMA). The essence of this improvement is also explained. Since the observation of the BKT transition has recently been reported in a two-dimensional (Formula presented.) Fermi gas, our results would be useful for the study of strong-coupling physics associated with this quasi-long-range order.

Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalJournal of Low Temperature Physics
DOIs
Publication statusAccepted/In press - 2016 Nov 9

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Keywords

  • BKT phase transition
  • Two-dimensional system
  • Ultracold Fermi gas

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Pseudogap Phenomena Near the BKT Transition of a Two-Dimensional Ultracold Fermi Gas in the Crossover Region. / Matsumoto, M.; Hanai, R.; Inotani, Daisuke; Ohashi, Yoji.

In: Journal of Low Temperature Physics, 09.11.2016, p. 1-9.

Research output: Contribution to journalArticle

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N2 - We investigate strong-coupling properties of a two-dimensional ultracold Fermi gas in the normal phase. In the three-dimensional case, it has been shown that the so-called pseudogap phenomena can be well described by a (non-self-consistent) T-matrix approximation (TMA). In the two-dimensional case, while this strong-coupling theory can explain the pseudogap phenomenon in the strong-coupling regime, it unphysically gives large pseudogap size in the crossover region, as well as in the weak-coupling regime. We show that this difficulty can be overcome when one improves TMA to include higher-order pairing fluctuations within the framework of a self-consistent T-matrix approximation (SCTMA). The essence of this improvement is also explained. Since the observation of the BKT transition has recently been reported in a two-dimensional (Formula presented.) Fermi gas, our results would be useful for the study of strong-coupling physics associated with this quasi-long-range order.

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