Quantum annealing with a nonvanishing final value of the transverse field

TL;DR

This paper demonstrates that stopping quantum annealing with a non-zero transverse field can better infer the original ground state of a noisy spin-glass Hamiltonian, as finite quantum fluctuations mitigate noise effects.

Contribution

It reveals that halting quantum annealing before the transverse field reaches zero improves ground state inference in noisy conditions, supported by numerical and analytical results.

Findings

Stopping annealing early reduces Hamming distance to original ground state.

Finite quantum fluctuations help counteract noise effects.

Results are supported by numerical simulations and mean-field analysis.

Abstract

We study the problem to infer the original ground state of a spin-glass Hamiltonian out of the information from the Hamiltonian with interactions deviated from the original ones. Our motivation comes from quantum annealing on a real device in which the values of interactions are degraded by noise. We show numerically for quasi-one-dimensional systems that the Hamming distance between the original ground state and the inferred spin state is minimized when we stop the process of quantum annealing before the amplitude of the transverse field reaches zero in contrast to the conventional prescription. This result means that finite quantum fluctuations compensate for the effects of noise, at least to some extent. Analytical calculations using the infinite-range mean-field model support our conclusion qualitatively.