Dynamics-induced freezing of strongly correlated ultracold bosons

¹ Theoretical Physics Department, Indian Association for the Cultivation of Science Jadavpur, Kolkata-700032, India
² Department of Physics, California Institute of Technology - Pasadena, CA 91125, USA

Received: 23 August 2012
Accepted: 27 November 2012

Abstract

We study the non-equilibrium dynamics of ultracold bosons in an optical lattice with a time-dependent hopping amplitude J(t) = J₀ + δJcos(ωt) which takes the system from a superfluid phase near the Mott-superfluid transition (J = J₀ + δJ) to a Mott phase (J = J₀ − δJ) and back through a quantum critical point (J = J_c), and demonstrate dynamics-induced freezing of the boson wave function at specific values of ω. At these values, the wave function overlap F (defect density P = 1 − F) approaches unity (zero). We provide a qualitative explanation of the freezing phenomenon, show its robustness against quantum fluctuations and the presence of a trap, compute residual energy and superfluid order parameter for such dynamics, and suggest experiments to test our theory.