Quantum-to-classical reduction of quantum master equations

A general method of quantum-to-classical reduction of quantum dynamics is described. The key aspect of our method is the similarity transformation of the Liouvillian, which provides a new perspective. In conventional studies of quantum energy transport, the rotating wave approxima-tion has frequently been regarded as an inappropriate approach because it causes the energy flow through the system to vanish. Our formulation elucidates why this unphysical result occurs and provides a solution for the problem. That is, not only the density matrix but also the physi-cal quantity is to be transformed. Moreover, we show that quantum dynamics can be “exactly” replaced with classical equations for the calculation of the transport efficiency. Subject Index A5