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

Sato, Ryohei; Kagamihara, Daichi; Manabe, Koki; Inotani, Daisuke; Ōhashi, Y.

doi:10.1007/s10909-018-2103-0

Cited by 1 publication

(2 citation statements)

References 16 publications

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“…10(c). Similar diagrams have also been discussed as the origin of an effective interaction between Cooper-pairs in the BEC regime of a two-component Fermi gas [41,[76][77][78][79]. In this paper, to analytically sum up the diagrams in Fig.…”

Section: B Strong-coupling Side: Composite Fermi-molecular Gasmentioning

confidence: 83%

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Thermodynamic stability, compressibility matrix, and effects of mediated interactions in a strongly-interacting Bose-Fermi mixture

Manabe,

Ohashi

2021

Preprint

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We theoretically investigate the thermodynamic stability of a normal-state Bose-Fermi mixture, with a tunable Bose-Fermi pairing interaction −U BF < 0 associated with a hetero-nuclear Feshbach resonance, as well as a weak repulsive Bose-Bose interaction U BB ≥ 0. Including strong heteropairing fluctuations associated with the former interaction within the self-consistent T -matrix approximation, as well as the latter within the mean-field level, we calculate the compressibility matrix, to assess the stability of this system against density fluctuations. In the weak-and the intermediate-coupling regime with respect −U BF , we show that an effective attractive interaction between bosons mediated by density fluctuations in the Fermi component makes the system unstable below a certain temperature T clp (leading to density collapse). When U BB = 0, T clp is always higher than the Bose-Einstein condensation (BEC) temperature T c . When U BB > 0, the density collapse is suppressed, and the BEC transition becomes possible. It is also suppressed by the formation of tightly bound Bose-Fermi molecules when the hetero-pairing interaction −U BF is strong; however, since the system may be viewed as a molecular Fermi gas in this case, the BEC transition does not also occur. Since quantum gases involving Bose atoms are known to be sensitive to inter-particle correlations, our results would be useful for the study of many-body properties of a Bose-Fermi mixture in a stable manner, without facing the unwanted density collapse.Recently, Bose-Fermi mixtures have attracted much attention in cold atom physics [1][2][3][4][5][6][7]. Since one can tune the strength of a Bose-Fermi pairing interaction by adjusting the threshold energy of a hetero-nuclear Feshbach resonance[8], strong-coupling properties of this gas mixture have been studied [9][10][11][12][13]. In addition, tuning of an effective Bose-Bose (Fermi-Fermi) interaction mediated by Fermi (Bose) component has also been discussed [14][15][16][17]. As an interesting possibility, a non-s-wave Fermi superfluid induced by such a boson-mediated pairing interaction has recently been proposed [18][19][20].Bose-Fermi mixtures have also been discussed in other research fields, e.g., 3 He-4 He mixture [21][22][23], as well as a high-density QCD matter[24] (where the system is regarded as a mixture of bound di-quarks (bosons) and unpaired quarks (fermions)). In condensed matter physics, as a possible route to reach high-temperature superconductivity, a nano-device consisting of a n-doped semiconductor (electron gas) immersed in an exciton-polariton BEC (bosons) has theoretically been proposed [25][26][27]. Since a Bose-Fermi mixture in cold atom physics is simple and highly tunable, this dilute gas system is expected as a useful quantum simulator [28] for the study of these more complicated many-body quantum systems.In considering a Bose-Fermi mixture with a hetero-nuclear Feshbach resonance, besides strong-coupling effects caused by a Feshbach-induced tunable interaction, thermodynamic s...

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Section: B Strong-coupling Side: Composite Fermi-molecular Gasmentioning

confidence: 83%

“…We briefly note that a similar "molecular mapping" has also been discussed in the BEC regime of a two-component Fermi gas (where composite molecules are bosons) [76,77].…”

Section: B Strong-coupling Side: Composite Fermi-molecular Gasmentioning

confidence: 87%

Thermodynamic stability, compressibility matrix, and effects of mediated interactions in a strongly-interacting Bose-Fermi mixture

Manabe,

Ohashi

2021

Preprint

View full text Add to dashboard Cite

show abstract

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

Cited by 1 publication

References 16 publications

Thermodynamic stability, compressibility matrix, and effects of mediated interactions in a strongly-interacting Bose-Fermi mixture

Thermodynamic stability, compressibility matrix, and effects of mediated interactions in a strongly-interacting Bose-Fermi mixture

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