Quantum transport in degenerate systems

TL;DR

This paper explores how the transfer rate in degenerate quantum systems depends on the angle between interaction vectors, revealing a cosine squared relationship and highlighting the competition between transport and dark state excitation.

Contribution

It demonstrates the dependence of quantum transport on the angle between bright vectors and links this to the excitation of dark states, advancing understanding of quantum coherence in nonequilibrium systems.

Findings

Flow is proportional to cosine squared of the angle between bright vectors.

Dark state excitation is proportional to sine squared of the angle.

Quantum transport and dark state excitation are competing processes.

Abstract

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.