Thermodynamics of the BCSBEC crossover
Abstract
We present a selfconsistent theory for the thermodynamics of the BCSBEC crossover in the normal and superfluid phase which is both conserving and gapless. It is based on the variational manybody formalism developed by Luttinger and Ward and by DeDominicis and Martin. Truncating the exact functional for the entropy to that obtained within a ladder approximation, the resulting selfconsistent integral equations for the normal and anomalous Green functions are solved numerically for arbitrary coupling. The critical temperature, the equation of state, and the entropy are determined as a function of the dimensionless parameter 1/k{sub F}a, which controls the crossover from the BCS regime of extended pairs to the BEC regime of tightly bound molecules. The tightly bound pairs turn out to be described by a Popovtype approximation for a dilute, repulsive Bose gas. Even though our approximation does not capture the critical behavior near the continuous superfluid transition, our results provide a consistent picture for the complete crossover thermodynamics which compares well with recent numerical and fieldtheoretic approaches at the unitarity point.
 Authors:
 Fachbereich Physik, Universitaet Konstanz, D78457 Konstanz (Germany)
 Institut fuer Theoretische Physik, Universitaet Innsbruck, Technikerstrasse 25, A6020 Innsbruck (Austria)
 Technische Universitaet Muenchen, JamesFranckStrasse, D85748 Garching (Germany)
 (Austria)
 Publication Date:
 OSTI Identifier:
 20982161
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevA.75.023610; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BCS THEORY; BOSEEINSTEIN CONDENSATION; BOSEEINSTEIN GAS; CAPTURE; COMPARATIVE EVALUATIONS; COUPLING; CRITICAL TEMPERATURE; ENTROPY; EQUATIONS OF STATE; GREEN FUNCTION; INTEGRAL EQUATIONS; LADDER APPROXIMATION; MANYBODY PROBLEM; MOLECULES; SUPERFLUIDITY; THERMODYNAMICS; VARIATIONAL METHODS
Citation Formats
Haussmann, R., Rantner, W., Cerrito, S., Institut fuer Theoretische Physik, Universitaet Innsbruck, Technikerstrasse 25, A6020 Innsbruck, and Zwerger, W.. Thermodynamics of the BCSBEC crossover. United States: N. p., 2007.
Web. doi:10.1103/PHYSREVA.75.023610.
Haussmann, R., Rantner, W., Cerrito, S., Institut fuer Theoretische Physik, Universitaet Innsbruck, Technikerstrasse 25, A6020 Innsbruck, & Zwerger, W.. Thermodynamics of the BCSBEC crossover. United States. doi:10.1103/PHYSREVA.75.023610.
Haussmann, R., Rantner, W., Cerrito, S., Institut fuer Theoretische Physik, Universitaet Innsbruck, Technikerstrasse 25, A6020 Innsbruck, and Zwerger, W.. Thu .
"Thermodynamics of the BCSBEC crossover". United States.
doi:10.1103/PHYSREVA.75.023610.
@article{osti_20982161,
title = {Thermodynamics of the BCSBEC crossover},
author = {Haussmann, R. and Rantner, W. and Cerrito, S. and Institut fuer Theoretische Physik, Universitaet Innsbruck, Technikerstrasse 25, A6020 Innsbruck and Zwerger, W.},
abstractNote = {We present a selfconsistent theory for the thermodynamics of the BCSBEC crossover in the normal and superfluid phase which is both conserving and gapless. It is based on the variational manybody formalism developed by Luttinger and Ward and by DeDominicis and Martin. Truncating the exact functional for the entropy to that obtained within a ladder approximation, the resulting selfconsistent integral equations for the normal and anomalous Green functions are solved numerically for arbitrary coupling. The critical temperature, the equation of state, and the entropy are determined as a function of the dimensionless parameter 1/k{sub F}a, which controls the crossover from the BCS regime of extended pairs to the BEC regime of tightly bound molecules. The tightly bound pairs turn out to be described by a Popovtype approximation for a dilute, repulsive Bose gas. Even though our approximation does not capture the critical behavior near the continuous superfluid transition, our results provide a consistent picture for the complete crossover thermodynamics which compares well with recent numerical and fieldtheoretic approaches at the unitarity point.},
doi = {10.1103/PHYSREVA.75.023610},
journal = {Physical Review. A},
number = 2,
volume = 75,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}

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