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

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

Research output: Contribution to journalArticlepeer-review


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
Pages (from-to)119-125
Number of pages7
JournalJournal of Low Temperature Physics
Issue number1-2
Publication statusPublished - 2019 Jul 15


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

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • General Materials Science
  • Condensed Matter Physics


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