Advantage of pausing: parameter setting for quantum annealers

TL;DR

This paper investigates the benefits of pausing during quantum annealing, demonstrating improved success probabilities and solution times across various problem classes and architectures, with guidelines for optimal parameter settings.

Contribution

It provides empirical evidence and qualitative guidelines for setting annealing parameters, especially pause timing and ferromagnetic coupling, on advanced quantum annealers.

Findings

Pausing improves success probability significantly.

Optimal pause parameters are robust across platforms.

Short pauses outperform longer annealing times.

Abstract

Prior work showed the efficacy of pausing midanneal: such a pause improved the probability of success by orders of magnitude in a class of native problem instances and improved the time to solution in a class of embedded problem instances. A physics-based picture provides qualitative suggestions for where pausing midanneal is effective, for the interplay between annealing schedule parameters and other annealing properties and parameters such as embedding size and strength of the ferromagnetic coupling $|J_F|$, and for the conditions under which pausing can improve the time to solution. Here, through demonstrations on an updated annealing architecture that has higher connectivity than previous annealers, and on multiple embedded problem classes, we are able to confirm various aspects of this picture. We demonstrate the robustness of the optimal pause parameters across platforms and problem classes, explore how to set $|J_F|$ to optimize performance in different scenarios, and provide empirical evidence that short pauses trump longer overall annealing times in time to solution. We also identify the number of different coefficients in a problem as a predictor of problem hardness, and explore its interplay with the optimal $|J_F|$ and embedding size. Based on these results we are able to present qualitative guidelines for parameter setting in quantum annealers.