Environment-assisted strong coupling regime

TL;DR

This paper shows that environmental interactions can enhance coupling in hybrid systems, allowing the strong coupling regime to persist even with high relaxation rates, by inducing additional coupling dependent on reservoir properties.

Contribution

It introduces the concept that environment-induced coupling can sustain strong coupling regimes, challenging the traditional view that environment always weakens coupling.

Findings

Environmental-induced coupling is proportional to Rabi coupling and reservoir density gradient.

A critical Rabi coupling exists above which strong coupling persists regardless of relaxation rate.

Managing reservoir density gradient offers a new control method for coupled systems.

Abstract

Strong coupling regime takes place in open hybrid systems consisting of two or more physical subsystems when the coupling strength between subsystems exceeds the relaxation rate. The relaxation arises due to the interaction of the system with environment. For this reason, it is usually believed that the enhancement of the interaction with environment inevitably leads to a transition of the system from the strong to weak coupling regime. In this paper, we refute this common opinion. We demonstrate the interaction of the coupled system with environment induces an additional coupling between the subsystems that contribute to retention the system in the strong coupling regime. We show that the environmental-induced coupling strength is proportional to the product of the Rabi coupling strength by the gradient of the density of states of the reservoir. There is a critical Rabi coupling strength above which the environmental-induced coupling ensures that the system remains in the strong coupling regime at any relaxation rate. In this case, the strong coupling regime takes place even when the relaxation rate is significantly above the Rabi coupling strength between the subsystems. The critical coupling depends on the gradient of the reservoir density of states. We demonstrate that managing this gradient can serve as an additional tool to control the properties of the coupled systems.