1. Isothermal compressibility and effects of multi-body molecular interactions in a strongly interacting ultracold Fermi gas
- Author
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Kagamihara, Daichi, Sato, Ryohei, Manabe, Koki, Tajima, Hiroyuki, and Ohashi, Yoji
- Subjects
Condensed Matter - Quantum Gases - Abstract
We theoretically investigate the isothermal compressibility $\kappa_{T}$ in the normal state of an ultracold Fermi gas. Including pairing fluctuations, as well as preformed-pair formations, within the framework of the self-consistent $T$-matrix approximation (SCTMA), we evaluate the temperature dependence of this thermodynamic quantity over the entire BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover region. While $\kappa_T$ in the weak-coupling BCS regime is dominated by Fermi atoms near the Fermi surface, correlations between tightly bound Cooper-pair molecules are found to play crucial roles in the strong-coupling BEC regime. In the latter region, besides a two-body molecular interaction, a three-body one is shown to sizably affect $\kappa_T$ near the superfluid phase transition temperature. Our results indicate that the strong-coupling BEC regime of an ultracold Fermi gas would provide a unique opportunity to study multi-body correlations between Cooper-pair molecules., Comment: 30 pages, 13 figures
- Published
- 2022
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