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Title: Two-band description of resonant superfluidity in atomic Fermi gases

Abstract

Fermionic superfluidity in atomic Fermi gases across a Feshbach resonance is normally described by the atom-molecule theory, which treats the closed channel as a noninteracting point boson. In this work we present a theoretical description of the resonant superfluidity in analogy to the two-band superconductors. We employ the underlying two-channel scattering model of Feshbach resonance where the closed channel is treated as a composite boson with binding energy ε 0 and the resonance is triggered by the microscopic interchannel coupling U 12. The binding energy ε 0 naturally serves as an energy scale of the system, which has been sent to infinity in the atom-molecule theory. We show that the atom-molecule theory can be viewed as a leading-order low-energy effective theory of the underlying fermionic theory in the limit ε 0→∞ and U 12→0, while keeping the phenomenological atom-molecule coupling finite. The resulting two-band description of the superfluid state is in analogy to the BCS theory of two-band superconductors. In the dilute limit ε 0→∞, the two-band description recovers precisely the atom-molecule theory. The two-band theory provides a natural approach to study the corrections because of a finite binding energy ε 0 in realistic experimental systems. For broad and moderatemore » resonances, the correction is not important for current experimental densities. However, for extremely narrow resonance, we find that the correction becomes significant. Lastly, the finite binding energy correction could be important for the stability of homogeneous polarized superfluid against phase separation in imbalanced Fermi gases across a narrow Feshbach resonance.« less

Authors:
 [1];  [2];  [2]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Swinburne Univ. of Technology, Victoria (Australia)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1246953
Alternate Identifier(s):
OSTI ID: 1180994
Report Number(s):
LA-UR-14-28538
Journal ID: ISSN 1050-2947; PLRAAN
Grant/Contract Number:
AC02-05CH11231; FT140100003; FT130100815; DP140103231; DP140100637; AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 91; Journal Issue: 2; Journal ID: ISSN 1050-2947
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Feshbach resonance; two-band superconductor; Fermi superfluidity

Citation Formats

He, Lianyi, Hu, Hui, and Liu, Xia -Ji. Two-band description of resonant superfluidity in atomic Fermi gases. United States: N. p., 2015. Web. doi:10.1103/PhysRevA.91.023622.
He, Lianyi, Hu, Hui, & Liu, Xia -Ji. Two-band description of resonant superfluidity in atomic Fermi gases. United States. doi:10.1103/PhysRevA.91.023622.
He, Lianyi, Hu, Hui, and Liu, Xia -Ji. Mon . "Two-band description of resonant superfluidity in atomic Fermi gases". United States. doi:10.1103/PhysRevA.91.023622. https://www.osti.gov/servlets/purl/1246953.
@article{osti_1246953,
title = {Two-band description of resonant superfluidity in atomic Fermi gases},
author = {He, Lianyi and Hu, Hui and Liu, Xia -Ji},
abstractNote = {Fermionic superfluidity in atomic Fermi gases across a Feshbach resonance is normally described by the atom-molecule theory, which treats the closed channel as a noninteracting point boson. In this work we present a theoretical description of the resonant superfluidity in analogy to the two-band superconductors. We employ the underlying two-channel scattering model of Feshbach resonance where the closed channel is treated as a composite boson with binding energy ε0 and the resonance is triggered by the microscopic interchannel coupling U12. The binding energy ε0 naturally serves as an energy scale of the system, which has been sent to infinity in the atom-molecule theory. We show that the atom-molecule theory can be viewed as a leading-order low-energy effective theory of the underlying fermionic theory in the limit ε0→∞ and U12→0, while keeping the phenomenological atom-molecule coupling finite. The resulting two-band description of the superfluid state is in analogy to the BCS theory of two-band superconductors. In the dilute limit ε0→∞, the two-band description recovers precisely the atom-molecule theory. The two-band theory provides a natural approach to study the corrections because of a finite binding energy ε0 in realistic experimental systems. For broad and moderate resonances, the correction is not important for current experimental densities. However, for extremely narrow resonance, we find that the correction becomes significant. Lastly, the finite binding energy correction could be important for the stability of homogeneous polarized superfluid against phase separation in imbalanced Fermi gases across a narrow Feshbach resonance.},
doi = {10.1103/PhysRevA.91.023622},
journal = {Physical Review. A},
number = 2,
volume = 91,
place = {United States},
year = {Mon Feb 23 00:00:00 EST 2015},
month = {Mon Feb 23 00:00:00 EST 2015}
}

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Cited by: 3 works
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