Condensed Matter Seminar Series

Title: Equilibrium and Emergent Quantum Criticality in Ultracold Gases on Optical Lattices

Marcos Rigol

University of California at Davis

Thursday Feb. 23,  11:30 am,  Room 298,  Physics Building

Abstract:   In this talk we will discuss ground state properties and the non-equilibrium dynamics of strongly correlated quantum gases confined on optical lattices. Such systems, achieved in recent experiments trapping either bosons or fermions, can be considered as almost ideal realizations of the boson or fermion Hubbard model, respectively. We will show that due to the inhomogeneous character of the confined gas, local compressible and incompressible domains can coexist in spatially separated regions. As a consequence, the global superfluid(metal)--Mott-insulator quantum phase transition, which occurs in the periodic case, is destroyed by the trap. Quantum critical behavior is, however, observed at the boundaries of the coexisting phases. Further, we discuss exact results for the non-equilibrium dynamics of hard-core bosons in one dimension. We will analyse how coherence develops during the expansion of Mott-insulating states producing the emergence of quasi-condensates of hard-core bosons at finite momentum. On the other hand, the expansion of an initial superfluid state produces a dynamical fermionization of the bosonic momentum distribution function.