A probability current analysis of energy transport in open quantum systems

We introduce a probability current analysis of excitation energy transfer between states of an open quantum system. Expressing the energy transfer through currents of excitation probability between the states in a site representation enables us to gain key insights into the energy transfer dynamics. It allows to, i) identify the pathways of energy transport in large networks of sites and to quantify their relative weights, ii) quantify the respective contributions of unitary dynamics, dephasing, and relaxation/dissipation processes to the energy transfer, and iii) quantify the contribution of coherence to the energy transfer. Our analysis is general and can be applied to a broad range of open quantum system descriptions (with coupling to non-Markovian environments) in a straightforward manner.