Quantum annealing of the $p$-spin model under inhomogeneous transverse field driving

TL;DR

This paper investigates how inhomogeneous transverse fields affect quantum annealing of the p-spin model, showing potential to avoid first-order phase transitions and offering insights into quantum versus classical annealing advantages.

Contribution

It demonstrates that inhomogeneous transverse field driving can prevent first-order transitions in quantum annealing of the p-spin model under ideal conditions.

Findings

Inhomogeneous field can avoid first-order transitions at zero temperature.

Quantum advantage is limited but present under ideal conditions.

Classical spin-vector Monte Carlo shares the quantum phase diagram in the ideal case.

Abstract

We solve the mean-field-like $p$-spin Ising model under a spatio-temporal inhomogeneous transverse field to study the effects of inhomogeneity on the performance of quantum annealing. We find that the problematic first-order quantum phase transition that arises under the conventional homogeneous field protocol can be avoided if the temperature is zero and the local field is completely turned off site by site after a finite time. When these ideal conditions are not satisfied, a new series of first-order transitions appear, which prevents us from driving the system while avoiding first-order transitions. Nevertheless, under these non-ideal conditions, quantitative improvements can be obtained in terms of narrower tunneling barriers in the free energy landscape. A comparison with classical simulated annealing establishes a limited quantum advantage in the ideal case, since inhomogeneous temperature driving in simulated annealing cannot remove a first-order transition, in contrast to the quantum case. The classical model of spin-vector Monte Carlo is also analyzed, and we find it to have the same thermodynamic phase diagram as the quantum model in the ideal case, with deviations arising at non-zero temperature.