Sreda 19. avgust 2009. godine u 13 casova
Fizicki amfiteatar, sala 661, III sprat, Studentski trg 12.
Carlos A. R. Sa de Melo
Georgia Institute of Technology, Atlanta, GA, USA
"Evolution from BCS to BKT superfluidity in one-dimensional optical lattices"
The finite temperature phase diagram of fermions mixtures in one dimensional optical lattices as a function of interaction strength is analyzed. At low temperatures, the system evolves from an anisotropic three-dimensional (3D) Bardeen-Copper-Schrieffer BCS) superfluid to an effectively two-dimensional (2D) Berezinskii-Kosterlitz-Thouless BKT) superfluid as the interaction strength increases. The critical temperature as a function of interaction strength is calculated and the region where the dimensional crossover from anisotropic 3D to 2D superfluid is determined for a specified optical lattice potential. Finally, it is shown that the dominant vortex excitations near the critical temperature evolve from multiplane elliptical vortex loops in the 3D regime to planar vortex-antivortex pair in the 2D regime.