We investigate the crossover from Bardeen-Cooper-Schrieffer (BCS) superfluidity to Bose-Einstein condensation (BEC) in a two-dimensional Fermi gas at T = 0 using the fixed-node diffusion Monte Carlo method. We calculate the equation of state and the gap parameter as a function of the interaction strength, observing large deviations compared to mean-field predictions. In the BEC regime our results show the important role of dimer-dimer and atom-dimer interaction effects that are completely neglected in the mean-field picture.We also consider the highly polarized gas and the competition between a polaronic and a molecular picture.

BCS-BEC crossover in two dimensions: A quantum Monte Carlo study / G. Bertaina - In: LECTURES ON THE PHYSICS OF STRONGLY CORRELATED SYSTEMS XVI: Sixteenth Training Course in the Physics of Strongly Correlated Systems / [a cura di] A.Avella, F. Mancini. - [s.l] : American Institute of Physics, 2011. - pp. 286-290 (( Intervento presentato al XVI. convegno PHYSICS OF STRONGLY CORRELATED SYSTEMS XVI: Sixteenth Training Course in the Physics of Strongly Correlated Systems tenutosi a Vietri sul Mare (Salerno), Italia nel 2011 [10.1063/1.4755827].

BCS-BEC crossover in two dimensions: A quantum Monte Carlo study

G. Bertaina
Primo
2011

Abstract

We investigate the crossover from Bardeen-Cooper-Schrieffer (BCS) superfluidity to Bose-Einstein condensation (BEC) in a two-dimensional Fermi gas at T = 0 using the fixed-node diffusion Monte Carlo method. We calculate the equation of state and the gap parameter as a function of the interaction strength, observing large deviations compared to mean-field predictions. In the BEC regime our results show the important role of dimer-dimer and atom-dimer interaction effects that are completely neglected in the mean-field picture.We also consider the highly polarized gas and the competition between a polaronic and a molecular picture.
BCS-BEC crossover; Quantum Monte Carlo; low dimensionality
Settore FIS/03 - Fisica della Materia
Settore FIS/02 - Fisica Teorica, Modelli e Metodi Matematici
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/250777
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