Steady state thermodynamics of two qubits strongly coupled to bosonic environments

TL;DR

This paper explores the steady states of two strongly coupled qubits in bosonic environments, showing that environment-induced decoherence alters the expected Gibbs state and can suppress heat conduction.

Contribution

It introduces a new perspective on steady states under strong coupling, incorporating environment-induced decoherence and the einselection framework.

Findings

Gibbs state is projected onto the pointer basis due to continuous measurement.

Strong coupling can suppress heat conduction in non-equilibrium steady states.

Numerical simulations support the theoretical postulate.

Abstract

When a quantum system is placed in thermal environments, we often assume that the system relaxes to the Gibbs state in which decoherence takes place in the system energy eigenbasis. However, when the coupling between the system and the environments is strong, the stationary state is not necessarily the Gibbs state due to environment-induced decoherence which can be interpreted as continuous measurement by the environments. Based on the einselection proposed by Zurek, we postulate that the Gibbs state is projected onto the pointer basis due to the continuous measurement. We justify the proposition by exact numerical simulation of a pair of coupled qubits interacting with boson gases. Furthermore, we demonstrate that heat conduction in non-equilibrium steady states can be suppressed in the strong coupling limit also by the environment-induced decoherence.