Strong-Coupling Effects on Specific Heat in the BCS–BEC Crossover

Daisuke Inotani; Pieter van Wyk; Yoji Ohashi

doi:10.1007/s10909-019-02194-7

Strong-Coupling Effects on Specific Heat in the BCS–BEC Crossover

Daisuke Inotani, Pieter van Wyk, Yoji Ohashi

Department of Physics

Research output: Contribution to journal › Article › peer-review

Abstract

We theoretically investigate strong-coupling effects on specific heat at constant volume C_V in a superfluid Fermi gas with a tunable interaction associated with Feshbach resonance. Including fluctuations of the superfluid order parameter within the strong-coupling theory developed by Nozières and Schmitt-Rink, we calculate the temperature dependence of C_V at the unitarity limit in the superfluid phase. We show that, in the low-temperature region, T³-behavior is shown in the temperature dependence of C_V. This result indicates that the low-lying excitations are dominated by the gapless Goldstone mode, associated with the phase fluctuations of the superfluid order parameter. Since the Goldstone mode is one of the most fundamental phenomena in the Fermionic superfluidity, our results are useful for further understanding how the pairing fluctuations affect physical properties in the BCS–BEC crossover physics below the superfluid transition temperature.

Original language	English
Pages (from-to)	111-118
Number of pages	8
Journal	Journal of Low Temperature Physics
Volume	196
Issue number	1-2
DOIs	https://doi.org/10.1007/s10909-019-02194-7
Publication status	Published - 2019 Jul 15

Keywords

BCS–BEC crossover
Goldstone mode
Specific heat
Ultracold Fermi gas

ASJC Scopus subject areas

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

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10.1007/s10909-019-02194-7

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title = "Strong-Coupling Effects on Specific Heat in the BCS–BEC Crossover",

abstract = "We theoretically investigate strong-coupling effects on specific heat at constant volume CV in a superfluid Fermi gas with a tunable interaction associated with Feshbach resonance. Including fluctuations of the superfluid order parameter within the strong-coupling theory developed by Nozi{\`e}res and Schmitt-Rink, we calculate the temperature dependence of CV at the unitarity limit in the superfluid phase. We show that, in the low-temperature region, T3-behavior is shown in the temperature dependence of CV. This result indicates that the low-lying excitations are dominated by the gapless Goldstone mode, associated with the phase fluctuations of the superfluid order parameter. Since the Goldstone mode is one of the most fundamental phenomena in the Fermionic superfluidity, our results are useful for further understanding how the pairing fluctuations affect physical properties in the BCS–BEC crossover physics below the superfluid transition temperature.",

keywords = "BCS–BEC crossover, Goldstone mode, Specific heat, Ultracold Fermi gas",

author = "Daisuke Inotani and {van Wyk}, Pieter and Yoji Ohashi",

note = "Funding Information: Acknowledgements This work was supported by KiPAS project in Keio University. DI was supported by Grant-in-aid for Scientific Research from JSPS in Japan (No. JP16K17773). YO was supported by Grant-in-aid for Scientific Research from MEXT and JSPS in Japan (Nos. JP18K11345, JP18H05406, JP16K05503). Funding Information: This work was supported by KiPAS project in Keio University. DI was supported by Grant-in-aid for Scientific Research from JSPS in Japan (No. JP16K17773). YO was supported by Grant-in-aid for Scientific Research from MEXT and JSPS in Japan (Nos. JP18K11345, JP18H05406, JP16K05503). Publisher Copyright: {\textcopyright} 2019, Springer Science+Business Media, LLC, part of Springer Nature.",

year = "2019",

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doi = "10.1007/s10909-019-02194-7",

language = "English",

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journal = "Journal of Low Temperature Physics",

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AU - Inotani, Daisuke

AU - van Wyk, Pieter

AU - Ohashi, Yoji

N1 - Funding Information: Acknowledgements This work was supported by KiPAS project in Keio University. DI was supported by Grant-in-aid for Scientific Research from JSPS in Japan (No. JP16K17773). YO was supported by Grant-in-aid for Scientific Research from MEXT and JSPS in Japan (Nos. JP18K11345, JP18H05406, JP16K05503). Funding Information: This work was supported by KiPAS project in Keio University. DI was supported by Grant-in-aid for Scientific Research from JSPS in Japan (No. JP16K17773). YO was supported by Grant-in-aid for Scientific Research from MEXT and JSPS in Japan (Nos. JP18K11345, JP18H05406, JP16K05503). Publisher Copyright: © 2019, Springer Science+Business Media, LLC, part of Springer Nature.

PY - 2019/7/15

Y1 - 2019/7/15

N2 - We theoretically investigate strong-coupling effects on specific heat at constant volume CV in a superfluid Fermi gas with a tunable interaction associated with Feshbach resonance. Including fluctuations of the superfluid order parameter within the strong-coupling theory developed by Nozières and Schmitt-Rink, we calculate the temperature dependence of CV at the unitarity limit in the superfluid phase. We show that, in the low-temperature region, T3-behavior is shown in the temperature dependence of CV. This result indicates that the low-lying excitations are dominated by the gapless Goldstone mode, associated with the phase fluctuations of the superfluid order parameter. Since the Goldstone mode is one of the most fundamental phenomena in the Fermionic superfluidity, our results are useful for further understanding how the pairing fluctuations affect physical properties in the BCS–BEC crossover physics below the superfluid transition temperature.

AB - We theoretically investigate strong-coupling effects on specific heat at constant volume CV in a superfluid Fermi gas with a tunable interaction associated with Feshbach resonance. Including fluctuations of the superfluid order parameter within the strong-coupling theory developed by Nozières and Schmitt-Rink, we calculate the temperature dependence of CV at the unitarity limit in the superfluid phase. We show that, in the low-temperature region, T3-behavior is shown in the temperature dependence of CV. This result indicates that the low-lying excitations are dominated by the gapless Goldstone mode, associated with the phase fluctuations of the superfluid order parameter. Since the Goldstone mode is one of the most fundamental phenomena in the Fermionic superfluidity, our results are useful for further understanding how the pairing fluctuations affect physical properties in the BCS–BEC crossover physics below the superfluid transition temperature.

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KW - Specific heat

KW - Ultracold Fermi gas

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Strong-Coupling Effects on Specific Heat in the BCS–BEC Crossover

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