Noise-Induced Thermalization in Quantum Systems

TL;DR

This paper shows that noise can actually accelerate the process of preparing Gibbs states in quantum systems, turning a typical obstacle into a beneficial feature for quantum computing.

Contribution

It demonstrates that noise can be exploited to speed up thermalization and Gibbs state preparation in quantum systems, providing a new paradigm for practical quantum computing.

Findings

Noise accelerates thermalization by ~3.5x in non-integrable models.

Noise enables thermalization in integrable models that normally do not thermalize.

Using noise for Gibbs state preparation offers practical advantages before fault-tolerance is achieved.

Abstract

In the current Noisy Intermediate-Scale Quantum era, noise is widely regarded as the primary obstacle to achieving fault-tolerant quantum computation. However, certain stages of the quantum computing pipeline can, in fact, benefit from this noise. In this work, we exploit the Eigenstate Thermalization Hypothesis to show that noise generically accelerates a fundamental task in quantum computing -- the preparation of Gibbs states. We demonstrate this behavior using classical and quantum simulations with Haar-random and phase-flip noise, respectively, on a spin-1/2 chain with a local Hamiltonian. Our non-integrable model sees ~3.5x faster thermalization in the presence of noise, while our integrable model, which would not otherwise thermalize, reaches a thermal state due to noise. Since certifying a local Gibbs state is relatively easy on a quantum computer, our approach provides a new practical solution to a key problem in quantum computing. More broadly, these results establish a new paradigm in which noise can be harnessed on quantum computers, enabling practical advantages before the years of fault-tolerance.