Impact of solvent on state-to-state population transport in multistate systems using coherences

TL;DR

This paper analyzes how solvents influence quantum transport pathways in multistate systems by linking coherences and populations, revealing complex solvent effects on transport routes in a model of the Fenna-Matthews-Olson complex.

Contribution

It introduces a rigorous method to account for both inter-site couplings and solvent effects on quantum transport pathways using coherence-population relations.

Findings

Solvent effects can significantly alter transport pathways without changing total populations.

Transport pathways are highly sensitive to local dissipative media.

The method reveals complex dynamics even in simple 4-site models.

Abstract

Understanding the pathways taken by a quantum particle during a transport process is an enormous challenge. There are broadly two different aspects of the problem that affect the route taken. First is obviously the couplings between the various sites, which translates into the intrinsic "strength" of a state-to-state channel. Apart from the inter-state couplings, the solvents affecting the energies of the state, and their relative coupling strengths and time-scales form the second factor. This impact of dissipative media is significantly more difficult to analyze. Building on recently derived relations between coherences and population derivatives, we present an analysis of the transport that allows us to account for both the effects in a rigorous manner. We demonstrate the richness hidden behind the transport even for a relatively simple system, a 4-site coarse-grained model of the Fenna-Matthews-Olson complex. The effect of the local dissipative media is highly non-trivial. We show that while the impact on the total site population may be small, there are dramatic changes to the pathway taken by the transport process. The ability to untangle the dynamics at a greater granularity opens up possibilities in terms of design of novel systems with an eye towards quantum control.