Isothermal Compressibility of an Ultracold Fermi Gas in the BCS–BEC Crossover

R. Sato, D. Kagamihara, K. Manabe, Daisuke Inotani, Yoji Ohashi

Research output: Contribution to journalArticle

Abstract

We theoretically investigate the isothermal compressibility κT in the normal state of an ultracold Fermi gas with a tunable attractive interaction. We calculate this thermodynamic quantity by considering fluctuations in the Cooper channel, within the framework of the self-consistent T-matrix approximation (SCTMA). For comparison, we also evaluate this quantity in a “non”-self-consistent T-matrix approximation (TMA). We show that the calculated κT diverges at Tc in the BCS–BEC crossover region. On the other hand, such a singular behavior is absent when we deal with this quantity in SCTMA. We point out that the origin of this difference is the neglect of an effective inter-pair interaction in the former approximation. We also explicitly show how such an interaction is involved in the theory when one deals with pairing fluctuations in SCTMA. Our results indicate that the isothermal compressibility is a useful quantity in considering how preformed Cooper pairs interact with one another in the BCS–BEC crossover regime of an ultracold Fermi gas.

Original languageEnglish
JournalJournal of Low Temperature Physics
DOIs
Publication statusAccepted/In press - 2018 Jan 1

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Compressibility
compressibility
crossovers
Gases
approximation
gases
Thermodynamics
interactions
thermodynamics

Keywords

  • Isothermal compressibility
  • Repulsive inter-pair interaction
  • Ultracold Fermi gas

ASJC Scopus subject areas

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

Cite this

Isothermal Compressibility of an Ultracold Fermi Gas in the BCS–BEC Crossover. / Sato, R.; Kagamihara, D.; Manabe, K.; Inotani, Daisuke; Ohashi, Yoji.

In: Journal of Low Temperature Physics, 01.01.2018.

Research output: Contribution to journalArticle

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N2 - We theoretically investigate the isothermal compressibility κT in the normal state of an ultracold Fermi gas with a tunable attractive interaction. We calculate this thermodynamic quantity by considering fluctuations in the Cooper channel, within the framework of the self-consistent T-matrix approximation (SCTMA). For comparison, we also evaluate this quantity in a “non”-self-consistent T-matrix approximation (TMA). We show that the calculated κT diverges at Tc in the BCS–BEC crossover region. On the other hand, such a singular behavior is absent when we deal with this quantity in SCTMA. We point out that the origin of this difference is the neglect of an effective inter-pair interaction in the former approximation. We also explicitly show how such an interaction is involved in the theory when one deals with pairing fluctuations in SCTMA. Our results indicate that the isothermal compressibility is a useful quantity in considering how preformed Cooper pairs interact with one another in the BCS–BEC crossover regime of an ultracold Fermi gas.

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