March, 27 (2006) at 4pm

Charles Creffield
University College London

The experimental realization of Bose-Einstein condensation in dilute atomic gases, first achieved in 1995, has led to a huge surge of interest in the properties of this unusual state of matter. When confined in an optical lattice, the dynamics of a Bose-Einstein condensate can be described by a Bose-Hubbard model, the parameters of which can be controlled by varying the intensity of the laser fields. In this talk I will show how applying an additional peridic driving field to the confining potential can profoundly modify the dynamics of the system, and how this can be understood by means of Floquet theory. In particular, when the driving frequency is resonant with the depth of the trapping potential, the quantum phase transition from a Mott insulator to a superfluid state can be very delicately controlled by the strength of the driving field. I will further show how the form of the field can be chosen to maximize this effect, and thus how the entanglement and localization properties of a Bose-Einstein condensate can be manipulated by time-dependent fields.