977 research outputs found
Theory of Non-Equilibrium Sationary States as a Theory of Resonances
We study a small quantum system (e.g. a simplified model for an atom or
molecule) interacting with two bosonic or fermionic reservoirs (say, photon or
phonon fields). We show that the combined system has a family of stationary
states, parametrized by two numbers , (``reservoir temperatures'').
If , then these states are non-equilibrium, stationary states
(NESS). In the latter case we show that they have nonvanishing heat fluxes and
positive entropy production. Furthermore, we show that these states are
dynamically asymptotically stable. The latter means that the evolution with an
initial condition, normal with respect to any state where the reservoirs are in
equilibria at temperatures and , converges to the corresponding
NESS. Our results are valid for the temperatures satisfying the bound
, where is the coupling constant and is a power related to the infra-red behaviour of the coupling
functions.Comment: 1 figure. To appear in Ann. H. Poincar
Resonant Perturbation Theory of Decoherence and Relaxation of Quantum Bits
We describe our recent results on the resonant perturbation theory of
decoherence and relaxation for quantum system with many qubits. The approach
represents a rigorous analysis of the phenomenon of decoherence and relaxation
for general -level systems coupled to reservoirs of the bosonic fields. We
derive a representation of the reduced dynamics valid for all times
and for small but fixed interaction strength. Our approach does not involve
master equation approximations and applies to a wide variety of systems which
are not explicitly solvable
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