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Center for Nonlinear Studies |
A fundamental question in quantum statistical mechanics is: What quantum systems of many degrees of freedom are able to function as a heat bath and thus thermally equilibrate (and "decohere") themselves? The idea that certain infinite and strongly-interacting disordered systems are localized and fail to thermally equilibrate themselves at nonzero temperature is due to Anderson (1958). The Anderson localization transition with interactions and at nonzero temperature is a quantum phase transition between this localized phase and the "ergodic" phase that does succeed in thermally equilbrating itself and thus apparently obeys the "eigenstate thermalization hypothesis". The many-body localized phase is an interesting potential quantum memory: it has local two-level systems that constitute "permanent" q-bits with infinite coherence time, even though they are interacting strongly with many other degrees of freedom. Approximations to this physics might be realized with spins in solids (as Anderson originally considered) or with cold atoms in a random optical lattice.
Host: Armin Rahmanisisan