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Title: Properties of strongly paired fermionic condensates

Abstract

We study a gas of fermions undergoing a wide resonance s-wave BCS-Bose-Einstein-condensate (BEC) crossover, in the BEC regime at zero temperature. We calculate the chemical potential and the speed of sound of this Bose-Einstein-condensed gas, as well as the condensate depletion, in the low-density approximation. We discuss how higher-order terms in the low-density expansion can be constructed. We demonstrate that the standard BCS-BEC gap equation is invalid in the BEC regime and is inconsistent with the results obtained here. The low-density approximation we employ breaks down in the intermediate BCS-BEC crossover region. Hence our theory is unable to predict how the chemical potential and the speed of sound evolve once the interactions are tuned towards the BCS regime. As a part of our theory, we derive the well-known result for the bosonic scattering length diagrammatically and check that there are no bound states of two bosons.

Authors:
;  [1]
  1. Department of Physics, CB390, University of Colorado, Boulder, Colorado, 80309 (United States)
Publication Date:
OSTI Identifier:
20787288
Resource Type:
Journal Article
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 73; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevA.73.053607; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1050-2947
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; APPROXIMATIONS; BCS THEORY; BOSE-EINSTEIN CONDENSATION; BOUND STATE; DENSITY; EXPANSION; FERMIONS; POTENTIALS; RESONANCE; S WAVES; SCATTERING LENGTHS; SOUND WAVES; VELOCITY

Citation Formats

Levinsen, J, and Gurarie, V. Properties of strongly paired fermionic condensates. United States: N. p., 2006. Web. doi:10.1103/PHYSREVA.73.0.
Levinsen, J, & Gurarie, V. Properties of strongly paired fermionic condensates. United States. https://doi.org/10.1103/PHYSREVA.73.0
Levinsen, J, and Gurarie, V. Mon . "Properties of strongly paired fermionic condensates". United States. https://doi.org/10.1103/PHYSREVA.73.0.
@article{osti_20787288,
title = {Properties of strongly paired fermionic condensates},
author = {Levinsen, J and Gurarie, V},
abstractNote = {We study a gas of fermions undergoing a wide resonance s-wave BCS-Bose-Einstein-condensate (BEC) crossover, in the BEC regime at zero temperature. We calculate the chemical potential and the speed of sound of this Bose-Einstein-condensed gas, as well as the condensate depletion, in the low-density approximation. We discuss how higher-order terms in the low-density expansion can be constructed. We demonstrate that the standard BCS-BEC gap equation is invalid in the BEC regime and is inconsistent with the results obtained here. The low-density approximation we employ breaks down in the intermediate BCS-BEC crossover region. Hence our theory is unable to predict how the chemical potential and the speed of sound evolve once the interactions are tuned towards the BCS regime. As a part of our theory, we derive the well-known result for the bosonic scattering length diagrammatically and check that there are no bound states of two bosons.},
doi = {10.1103/PHYSREVA.73.0},
url = {https://www.osti.gov/biblio/20787288}, journal = {Physical Review. A},
issn = {1050-2947},
number = 5,
volume = 73,
place = {United States},
year = {2006},
month = {5}
}