2 research outputs found
Entropy of a Quantum Oscillator coupled to a Heat Bath and implications for Quantum Thermodynamics
The free energy of a quantum oscillator in an arbitrary heat bath at a
temperature T is given by a "remarkable formula" which involves only a single
integral. This leads to a corresponding simple result for the entropy. The low
temperature limit is examined in detail and we obtain explicit results both for
the case of an Ohmic heat bath and a radiation heat bath. More general heat
bath models are also examined. This enables us to determine the entropy at zero
temperature in order to check the third law of thermodynamics in the quantum
regimeComment: International Conference on "Frontiers of Quantum and Mesoscopic
Thermodynamics
Decoherence in Nanostructures and Quantum Systems
Decoherence phenomena are pervasive in the arena of nanostructures but
perhaps even more so in the study of the fundamentals of quantum mechanics and
quantum computation. Since there has been little overlap between the studies in
both arenas, this is an attempt to bridge the gap. Topics stressed include (a)
wave packet spreading in a dissipative environment, a key element in all
arenas, (b) the definition of a quantitative measure of decoherence, (c) the
near zero and zero temperature limit, and (d) the key role played by initial
conditions: system and environment entangled at all times so that one must use
the density matrix (or Wigner distribution) for the complete system or
initially decoupled system and environment so that use of a reduced density
matrix or reduced Wigner distribution is feasible. Our approach utilizes
generalized quantum Langevin equations and Wigner distributions