BCS-BEC crossover in two dimensions: A quantum Monte Carlo study
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.
- Publication:
-
Lectures on the Physics of Strongly Correlated Systems XVI: Sixteenth Training Course in the Physics of Strongly Correlated Systems
- Pub Date:
- September 2012
- DOI:
- 10.1063/1.4755827
- Bibcode:
- 2012AIPC.1485..286B
- Keywords:
-
- BCS theory;
- Bose-Einstein condensation;
- diffusion;
- equations of state;
- fermion systems;
- Monte Carlo methods;
- superfluidity;
- 02.70.Ss;
- 03.75.Kk;
- 05.30.Fk;
- 05.60.Gg;
- 05.70.Ce;
- Quantum Monte Carlo methods;
- Dynamic properties of condensates;
- collective and hydrodynamic excitations superfluid flow;
- Fermion systems and electron gas;
- Quantum transport;
- Thermodynamic functions and equations of state