Winton Brown, University of Sherbrooke Title: Thermalization and Quantum Information Theory.
University of Sherbrooke
Title: Thermalization and Quantum Information Theory.
Abstract: The simplest way to think of the approach to thermal equilibrium is that states that are originally distinguishable with respect to a restricted set of measurements (macrostates), become indistinguishable from an equilibrium state after the system has evolved for a sufficient amount of time. On the other hand, the condition for recovery of an encoded quantum memory is equivalent to the indistinguishability of the different quantum states of the code space with respect to the information the environment can obtain through interacting with the memory and thereby inducing noise. Thus, there is a direct analogy between a good encoding circuit for a quantum error correcting code and the process of thermalization under coherent unitary dynamics. Exploiting this analogy, I show that the quantum capacity of the erasure channel puts an upper bound on the size of the subspace of initial states that may thermalize under coherent evolution, and show that this bound is achieved by typical local dynamics in an amount of time that is only slightly larger than the minimum amount of time required for the dynamics to propagate a signal across the system.
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