Pairing properties of an odd-frequency superfluid Fermi gas

Fuente: arXiv
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Autori principali: Iwasaki, Shumpei, Kawamura, Taira, Manabe, Koki, Ohashi, Yoji
Natura: Preprint
Pubblicazione: 2024
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author Iwasaki, Shumpei
Kawamura, Taira
Manabe, Koki
Ohashi, Yoji
author_facet Iwasaki, Shumpei
Kawamura, Taira
Manabe, Koki
Ohashi, Yoji
contents We theoretically investigate strong-coupling properties of an odd-frequency Fermi superfluid. This pairing state has the unique property that Cooper pairs are formed between fermions, not at the same time, but at different times. To see whether or not such unequal-time pairs still exhibit bosonic behavior, we examine the space-time structure of the odd-frequency Cooper-pair wavefunction at $T=0$, by employing the combined path-integral formalism with the BCS-Eagles-Leggett-type superfluid theory. In the strong-coupling regime, the odd-frequency pair wavefunction still has different space-time structure from that in the ordinary even-frequency $s$-wave superfluid state, their $\textit{magnitudes}$ are found to become close to each other, except for the equal-time pairing component. In this regime, we also evaluate the superfluid phase transition temperature $T_{\rm c}$ within the framework of the strong-coupling theory developed by Nozières and Schmitt-Rink. The calculated $T_{\rm c}$ in the strong-coupling regime of the odd-frequency system is found to be well described by the Bose-Einstein condensation of tightly bound Bose molecules. Our results indicates that, in spite of vanishing equal-time pairing, odd-frequency Cooper pairs still behave like bosons in the strong-coupling regime, as in the even-frequency $s$-wave superfluid case.
format Preprint
id arxiv_https___arxiv_org_abs_2402_02222
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Pairing properties of an odd-frequency superfluid Fermi gas
Iwasaki, Shumpei
Kawamura, Taira
Manabe, Koki
Ohashi, Yoji
Quantum Gases
We theoretically investigate strong-coupling properties of an odd-frequency Fermi superfluid. This pairing state has the unique property that Cooper pairs are formed between fermions, not at the same time, but at different times. To see whether or not such unequal-time pairs still exhibit bosonic behavior, we examine the space-time structure of the odd-frequency Cooper-pair wavefunction at $T=0$, by employing the combined path-integral formalism with the BCS-Eagles-Leggett-type superfluid theory. In the strong-coupling regime, the odd-frequency pair wavefunction still has different space-time structure from that in the ordinary even-frequency $s$-wave superfluid state, their $\textit{magnitudes}$ are found to become close to each other, except for the equal-time pairing component. In this regime, we also evaluate the superfluid phase transition temperature $T_{\rm c}$ within the framework of the strong-coupling theory developed by Nozières and Schmitt-Rink. The calculated $T_{\rm c}$ in the strong-coupling regime of the odd-frequency system is found to be well described by the Bose-Einstein condensation of tightly bound Bose molecules. Our results indicates that, in spite of vanishing equal-time pairing, odd-frequency Cooper pairs still behave like bosons in the strong-coupling regime, as in the even-frequency $s$-wave superfluid case.
title Pairing properties of an odd-frequency superfluid Fermi gas
topic Quantum Gases
url https://arxiv.org/abs/2402.02222