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The general problem of Quantum Dissipation will be stated in the context
of an electron in a magnetic field. We will show how dissipation makes
the system move from the Landau regime to the Bohr-Van Leeuwen regime,
which may be viewed as a coherence to decoherence transition. We will
also discuss the specific heat and make some remarks on the Third Law of
Thermodynamics. The problem allows us to also compare and unify two
different approaches to Statistical Mechanics: the Gibbs and the
Einstein (Quantum Brownian Motion) approaches.
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