2008/03/04 by R. Jáuregui, Jauregui, R., R. Paredes +5
Physics and Astronomy · #Atomic and Subatomic Physics Research #Cold Atom Physics and Bose-Einstein Condensates #FOS: Physical sciences #Other Condensed Matter (cond-mat.other) #Physics of Superconductivity and Magnetism
paper · pdf · doi:10.48550/arxiv.0803.0559
openalex publication_date 2008/03/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We perform a variational quantum Monte Carlo simulation of the transition from a Bardeen-Cooper-Schrieffer superfluid (BCS) to a Bose-Einstein condensate (BEC) at zero temperature. The model Hamiltonian involves an attractive short range two body interaction and the atoms number 2N =330 is chosen so that, in the non-interacting limit, the ground state function corresponds to a closed shell configuration. The system is then characterized by the s-wave scattering length a of the two-particle collisions in the gas, which is varied from negative to positive values, and the Fermi wave number kF. Based on an extensive analysis of the s-wave two-body problem, one parameter variational many-body wave functions are proposed to describe the ground state of the interacting Fermi gas from BCS to BEC states. We exploit properties of antisymmetrized many-body functions to develop efficient techniques that permit variational calculations for a large number of particles. It is shown that a virial relation between the energy per particle and the trapping energy is approximately valid for -0.1<1/kFa<3.4. The influence of the harmonic trap and the interaction potential as exhibited in two-body correlation functions is also analyzed.