Finite-Temperature Pairing Gap of a Unitary Fermi Gas by Quantum Monte Carlo Calculations

Journal Article · Fri Nov 20 00:00:00 EST 2009 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.103.210403· OSTI ID:21370843

Magierski, Piotr; Wlazlowski, Gabriel ^[1]; Bulgac, Aurel; Drut, Joaquin E ^[2]

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1. Faculty of Physics, Warsaw University of Technology, ulica Koszykowa 75, 00-662 Warsaw (Poland)
2. Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States)

We calculate the one-body temperature Green's (Matsubara) function of the unitary Fermi gas via quantum Monte Carlo, and extract the spectral weight function A(p,omega) using the methods of maximum entropy and singular value decomposition. From A(p,omega) we determine the quasiparticle spectrum, which can be accurately parametrized by three functions of temperature: an effective mass m*, a mean-field potential U, and a gap DELTA. Below the critical temperature T{sub c}=0.15epsilon{sub F} the results for m*, U, and DELTA can be accurately reproduced using an independent quasiparticle model. We find evidence of a pseudogap in the fermionic excitation spectrum for temperatures up to T*{approx_equal}0.20{epsilon}{sub F}>T{sub c}.

• OSTI ID: 21370843
• Journal Information: Physical Review Letters, Vol. 103, Issue 21; Other Information: DOI: 10.1103/PhysRevLett.103.210403; (c) 2009 The American Physical Society; ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CRITICAL TEMPERATURE
EFFECTIVE MASS
ENTROPY
EXCITATION
FERMI GAS
GREEN FUNCTION
MEAN-FIELD THEORY
MONTE CARLO METHOD
QUANTUM MECHANICS
TEMPERATURE DEPENDENCE
WEIGHTING FUNCTIONS
CALCULATION METHODS
ENERGY-LEVEL TRANSITIONS
FUNCTIONS
MASS
MECHANICS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE