Reliability of the ginzburg-landau theory in the bcs-bec crossover by including gaussian fluctuations for 3d attractive fermions
Authors: Pascucci F.; Perali A.; Salasnich L.
Autors Affiliation: School of Science and Technology, Physics Division, University of Camerino, Via Madonna delle Carceri 9B, 62032 Camerino, Italy; Dipartimento di Fisica e Astronomia “”Galileo Galilei””, University of Padova, Via Marzolo 8, 35131 Padova, Italy; School of Pharmacy, Physics Unit, University of Camerino, Via Madonna delle Carceri 9B, 62032 Camerino, Italy; INO-CNR, Unita di Sesto Fiorentino, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy; INFN, Sezione di Padova, Via Marzolo 8, 35131 Padova, Italy
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.
Journal/Review: CONDENSED MATTER
Volume: 6 (4) Pages from: 49-1 to: 49-12
KeyWords: Ginzburg-Landau theory; BCS-BEC crossover; pair fluctuationsDOI: 10.3390/condmat6040049