Perfect quantum excitation energy transport via single edge perturbation in a complete network

TL;DR

This paper demonstrates that a single edge perturbation in a symmetric quantum network can achieve near-perfect excitation energy transport, with external noise sometimes enhancing efficiency, challenging traditional views on quantum transport.

Contribution

It introduces a method to significantly improve quantum excitation energy transport efficiency through minimal network perturbation and analyzes the role of noise in this process.

Findings

EET efficiency can reach 100% with a single edge perturbation.

Optimal energy transport occurs at a finite hopping rate.

External dephasing noise can enhance EET in localized networks.

Abstract

We consider quantum excitation energy transport (EET) in a network of two-state nodes in the Markovian approximation by employing the Lindblad formulation. We find that EET from an initial site, where the excitation is inserted to the sink, is generally inefficient due to the inhibition of transport by localization of the excitation wave packet in a symmetric, fully-connected network. We demonstrate that the EET efficiency can be significantly increased up to %100 by perturbing hopping transport between the initial node and the one connected directly to the sink, while the rate of energy transport is highest at a finite value of the hopping parameter. We also show that prohibiting hopping between the other nodes which are not directly linked to the sink does not improve the efficiency. We show that external dephasing noise in the network plays a constructive role for EET in the presence of localization in the network, while in the absence of localization it reduces the efficiency of EET.