Energy transport induced by transition from the weak to the strong coupling regime between non-Hermitian optical systems

Abstract

The strong coupling between non-Hermitian physical systems of different natures has been widely investigated recently since it endows them with new properties. In this work, we consider energy transport through an open quantum optical system consisting of strongly coupled subsystems. We use a partial-secular approach for the description of an open quantum system to investigate the system dynamics during the transition from a weak to a strong coupling regime with an increase of coupling between subsystems. On the example of strongly coupled two-level atoms, we show that during the transition to the strong coupling regime, the enhancement of energy transport through the open quantum system takes place. Namely, starting from zero value, when the coupling constant equals zero, the stationary energy flow increases and tends to an approximately constant value at the high values of the coupling constant. As a result, the specific energy flow—the stationary energy flow normalized to the coupling constant—reaches the maximum at some value of the coupling constant. This behavior takes place even in the case of the non-zero frequency detuning when there is no clear transition point from the weak to the strong coupling regime in the spectrum of system eigenvalues. Thus, to achieve significant energy flow through the compound open quantum system, it is sufficient to restrict the value of the coupling constant at which the specific energy flow is maximized. Also, we demonstrate the suppression of the stationary energy flow at high dissipation rates. The obtained results can be used in the design of quantum thermal devices.