Relaxation dynamics in double-spin systems

TL;DR

This paper investigates the relaxation dynamics of a two-spin system coupled to a common bosonic bath, revealing interference effects that influence long-term behavior and can enable reservoir cooling.

Contribution

It introduces a generalized master equation approach to simulate the dynamics and uncovers how interference effects affect relaxation and cooling in double-spin systems.

Findings

Interference effects significantly alter relaxation dynamics.

Long-time behavior depends on initial states and system parameters.

Coupling to multiple reservoirs can induce cooling mechanisms.

Abstract

We consider the relaxation dynamics of two spins coupled to a common bosonic bath. The time evolution is simulated by a generalized master equation derived within a real-time diagrammatic approach. Interference effects due to the coherent coupling to the common bath give rise to characteristic features in the relaxation dynamics after a quench or during a periodic external driving. In particular, we find that the long-time behavior during periodic driving depends sensitively on the initial state as well as on system parameters such as coupling asymmetries. When coupled to more than a single reservoir, the interference effects can lead to a cooling mechanism for one of the bosonic reservoirs.