Relaxation dynamics in the (double) sine-Gordon model: An open-system viewpoint

TL;DR

This paper investigates how breaking integrability affects the relaxation process in the (double) sine-Gordon model by modeling it as an open system with a quantum pendulum interacting with a phononic bath, revealing faster relaxation dynamics.

Contribution

It introduces an open-system perspective to study relaxation in the sine-Gordon model, separating phase fields into subsystem and environment, and applies a novel truncated Hamiltonian approach for real-time simulations.

Findings

Faster relaxation with integrability-breaking perturbations.

Increased entanglement and energy transfer in the perturbed model.

Open-system approach provides new insights into relaxation dynamics.

Abstract

We study the effects of integrability breaking on the relaxation dynamics of the (double) sine-Gordon model. Compared to previous studies, we apply an alternative viewpoint motivated by open-system physics by separating the phase field into homogeneous and inhomogeneous parts, describing a quantum pendulum (subsystem) and an interacting phononic bath (environment). To study the relaxation dynamics in the model, we perform quantum quenches using the mini-superspace-based truncated Hamiltonian approach developed recently and simulate the real-time evolution of various entanglement measures and the energy transfer between the subsystem and its environment. Our findings demonstrate that in the presence of integrability-breaking perturbations, the relaxation dynamics is substantially faster, signalled by the increase of entanglement and energy transfer between the quantum pendulum and the phonon bath.