Schedule Aug 24, 2012
Optimal Control of Quantum Evolution: State Preparation and Cooling Through Nonadiabatic Dynamics
Armin Rahmani (LANL)

We show that nonadiabatic unitary evolution with tailored time-dependent Hamiltonians can prepare systems of cold atomic gases with various desired properties: in particular, it can i) transform one ground state to another much faster than the adiabatic evolution, and, ii) extract energy from thermal states resulting in effective cooling beyond the current state of the art. We provide the following examples: 1) For a Luttinger liquid with tunable interaction strength, we find a dynamical phase transition, in which one ground state can be exactly transformed to another when the ratio of the preparation time to the system size exceeds a critical value. 2) For two one-dimensional quasi-condensates with tunable tunneling amplitude, we find nonadiabatic "bang-bang" protocols, which can effectively cool down one of the condensates below the initial temperature of the system.

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