Impact of Solvent on State-to-State Population Transport in Multistate Systems Using Coherences

Understanding the pathways taken by a quantum particleduring atransport process is an enormous challenge. There are broadly twodifferent aspects of the problem that affect the route taken. Firstis obviously the couplings between the various sites, which translatesinto the intrinsic "strength" of a state-to-state channel.Apart from these inter-state couplings, the relative coupling strengthsand timescales of the solvent modes form the second factor. This impactof the dissipative environment is significantly more difficult toanalyze. Building on the recently derived relations between coherencesand population derivatives, we present an analysis of the transportthat allows us to account for both the effects in a rigorous manner.We demonstrate the richness hidden behind the transport even for arelatively simple system, a 4-site coarse-grained model of the Fenna-Matthews-Olsoncomplex. The effect of the local dissipative media is highly nontrivial.We show that while the impact on the total site population may besmall, there are noticeable changes to the pathway taken by the transportprocess. We also demonstrate how an analysis in a similar spirit canbe done using the Fo''rster approximation. The ability to untanglethe dynamics at a greater granularity opens up possibilities in termsof design of novel systems with an eye toward quantum control.