Quantum sweeps, synchronization, and Kibble-Zurek physics in dissipative quantum spin systems

TL;DR

This paper explores how dissipation influences non-equilibrium quantum dynamics in spin systems, revealing phase transitions, synchronization effects, and Kibble-Zurek physics through exact stochastic methods.

Contribution

It introduces a precise stochastic approach to study dissipative quantum spin systems, analyzing phase transitions, synchronization, and Kibble-Zurek phenomena in both two-spin and many-spin scenarios.

Findings

Dissipation induces quantum phase transitions in spin systems.

Environment affects synchronization properties of spins.

Kibble-Zurek scaling applies to dissipative quantum spin arrays.

Abstract

We address dissipation effects on the non-equilibrium quantum dynamics of an ensemble of spins-1/2 coupled via an Ising interaction. Dissipation is modeled by a (ohmic) bath of harmonic oscillators at zero temperature and correspond either to the sound modes of a one-dimensional Bose-Einstein (quasi-)condensate or to the zero-point fluctuations of a long transmission line. We consider the dimer comprising two spins and the quantum Ising chain with long-range interactions, and develop a (mathematically and numerically) exact stochastic approach to address non-equilibrium protocols in the presence of an environment. For the two spin case, we first investigate the dissipative quantum phase transition induced by the environment through quantum quenches, and study the effect of the environment on the synchronization properties. Then, we address Landau-Zener-Stueckelberg-Majorana protocols for two spins, and for the spin array. In this latter case, we adopt a stochastic mean-field point of view and present a Kibble-Zurek type argument to account for interaction effects in the lattice. Such dissipative quantum spin arrays can be realized in ultra-cold atoms, trapped ions, mesoscopic systems, and are related to Kondo lattice models.