Schedule Aug 24, 2012
Stimulation of Quantum Phases by Time-dependent Perturbations
Victor Galitski (Univ. Maryland)

In this talk, I will review our recent theoretical work on dynamic stimulation of various quantum states. The general idea of this line of research is that the equilibrium distribution function (Fermi-Dirac of Bose-Einstein for fermions or bosons respectively) is rarely optimal for the occurrence of a given quantum state. A generic mean-field equation always contains a distribution function of excitations and therefore its solution in non-equilibrium can be viewed as a functional of the distribution function that falls into two categories: it can either suppress an interesting quantum property or on the contrary enhance it compared to equilibrium. Stimulation of a quantum state means finding an external perturbation that gives rise to the latter. This general idea will be illustrated on two examples: First, I will show how non-equilibrium enhancement of Cooper pairing can be achieved in cold fermion systems by applying carefully chosen using Bragg pulses. Second, dynamic stimulation of quantum coherence in periodically driven lattice bosons will be discussed. Finally, I will discuss how external time-dependent perturbations can be used to create and stabilize topological states.

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