On the optimal working point in dissipative quantum annealing

TL;DR

This paper investigates how a thermal environment influences quantum annealing in a transverse-field Ising chain, revealing conditions for an optimal annealing time that minimizes defects, relevant for experimental quantum annealing hardware.

Contribution

It demonstrates the existence of an optimal annealing time in dissipative quantum systems and maps the conditions under which this minimum defect density occurs.

Findings

Defect density shows a minimum at a specific annealing time.

Optimal working point depends on bath temperature and coupling strength.

Results are relevant for experimental quantum annealing implementations.

Abstract

We study the effect of a thermal environment on the quantum annealing dynamics of a transverse-field Ising chain. The environment is modelled as a single Ohmic bath of quantum harmonic oscillators weakly interacting with the total transverse magnetization of the chain in a translationally invariant manner. We show that the density of defects generated at the end of the annealing process displays a minimum as a function of the annealing time, the so-called optimal working point, only in rather special regions of the bath temperature and coupling strength plane. We discuss the relevance of our results for current and future experimental implementations with quantum annealing hardware.