Dynamical properties of a driven dissipative dimerized $S = 1/2$ chain

TL;DR

This paper develops a theoretical framework to analyze the nonequilibrium steady states of a driven, dissipative quantum spin chain coupled to phonons, providing insights into controlling many-body spin states in magnetic materials.

Contribution

It introduces a Lindblad formalism for a driven dissipative spin system coupled to phonons and characterizes the resulting nonequilibrium steady states under various parameters.

Findings

Identification of parameter regimes for stable NESS

Characterization of NESS frequency and wave-vector content

Analysis of transient dynamics and energy flow

Abstract

We consider the dynamical properties of a gapped quantum spin system coupled to the electric field of a laser, which drives the resonant excitation of specific phonon modes that modulate the magnetic interactions. We deduce the quantum master equations governing the time-evolution of both the lattice and spin sectors, by developing a Lindblad formalism with bath operators providing an explicit description of their respective phonon-mediated damping terms. We investigate the nonequilibrium steady states (NESS) of the spin system established by a continuous driving, delineating parameter regimes in driving frequency, damping, and spin-phonon coupling for the establishment of physically meaningful NESS and their related non-trivial properties. Focusing on the regime of generic weak spin-phonon coupling, we characterize the NESS by their frequency and wave-vector content, explore their transient and relaxation behavior, and discuss the energy flow, the system temperature, and the critical role of the type of bath adopted. Our study lays a foundation for the quantitative modelling of experiments currently being designed to control coherent many-body spin states in quantum magnetic materials.