Reliability of the Ginzburg-Landau Theory in the BCS-BEC Crossover by Including Gaussian Fluctuations for 3D Attractive Fermions

Abstract

We calculate the parameters of the Ginzburg-Landau (GL) equation of a three-dimensional attractive Fermi gas around the superfluid critical temperature. We compare different levels of approximation throughout the Bardeen-Cooper-Schrieffer (BCS) to the Bose-Einstein Condensate (BEC) regime. We show that the inclusion of Gaussian fluctuations strongly modifies the values of the Ginzburg-Landau parameters approaching the BEC regime of the crossover. We investigate the reliability of the Ginzburg-Landau theory, with fluctuations, studying the behavior of the coherence length and of the critical rotational frequencies throughout the BCS-BEC crossover. The effect of the Gaussian fluctuations gives qualitative correct trends of the considered physical quantities from the BCS regime up to the unitary limit of the BCS-BEC crossover. Approaching the BEC regime, the Ginzburg-Landau equation with the inclusion of Gaussian fluctuations turns out to be unreliable.

10 pages, 5 figures, published in Condensed Matter

References in corpus (8)

• Weakly bound dimers of fermionic atoms
• Quantum Fluctuations in the Superfluid State of the BCS-BEC Crossover
• Equation of state of a superfluid Fermi gas in the BCS-BEC crossover
• BCS-BEC crossover at finite temperature in the broken-symmetry phase
• The Josephson effect throughout the BCS-BEC crossover
• Temperature dependence of the pair coherence and healing lengths for a fermionic superfluid throughout the BCS-BEC crossover
• Quasi-one-dimensional system as a high-temperature superconductor
• Josephson effect with superfluid fermions in the two-dimensional BCS-BEC crossover

Cited by in corpus (2)

• BCS-BEC crossover of atomic Fermi superfluid in a spherical bubble trap
• Quench-induced spontaneous currents in rings of ultracold fermionic atoms