BCSBEC crossover in two dimensions: A quantum Monte Carlo study
Abstract
We investigate the crossover from BardeenCooperSchrieffer (BCS) superfluidity to BoseEinstein condensation (BEC) in a twodimensional Fermi gas at T = 0 using the fixednode 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 meanfield predictions. In the BEC regime our results show the important role of dimerdimer and atomdimer interaction effects that are completely neglected in the meanfield 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;
 BoseEinstein 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