Quantum transport in degenerate systems

Transport in nonequilibrium degenerate quantum systems is investigated. Transfer rate depends on parameters of the system. In this paper we investigate dependence of the flow (transfer rate) on the angle between "bright" vectors (which define interaction of the system with the environment). We show that in some approximation for the system under investigation the flow is proportional to cosine squared of the angle between "bright" vectors. Earlier in arXiv:1603.07182 it was shown that in this degenerate quantum system excitation of non-decaying quantum "dark" states is possible, moreover the effectiveness of this process is proportional to sine squared of the angle between "bright" vectors (this phenomenon was discussed as a possible model of excitation of quantum coherences in quantum photosynthesis). Thus quantum transport and excitation of dark states are competing processes, dark states can be considered as a result of leakage of quantum states in quantum thermodynamic machine which performs the quantum transport.