Dynamical quantum phase transitions in a noisy lattice gauge theory

TL;DR

This paper investigates the robustness of dynamical quantum phase transitions in a noisy lattice gauge theory, demonstrating that current quantum devices can effectively simulate these phenomena despite noise, with gauge invariance approximately maintained.

Contribution

It shows that a $(1+1)$D U$(1)$ quantum link model can be simulated under realistic noise conditions, revealing that noise effects can be understood and managed in quantum simulations.

Findings

Noise can be handled at realistic rates in NISQ devices.

Gauge-breaking noise leads to exponential damping without affecting key structures.

Quantum gauge theories can be studied with devices exhibiting only approximate gauge invariance.

Abstract

Lattice gauge theories (LGTs) form an intriguing class of theories highly relevant to both high-energy particle physics and low-energy condensed matter physics with the rapid development of engineered quantum devices providing new tools to study e.g. dynamics of such theories. The massive Schwinger model is known to exhibit intricate properties of more complicated theories and has recently been shown to undergo dynamical quantum phase transitions out of equilibrium. With current technology, noise is inevitable and potentially fatal for a successful quantum simulation. This paper studies the dynamics subject to noise of a $(1+1)$D U$(1)$ quantum link model following a quench of the sign of the mass term. We find that not only is the system capable of handling noise at rates realistic in NISQ-era devices, promising the possiblity to study the target dynamics with current technology, but the effect of noise can be understood in terms of simple models. Specifically the gauge-breaking nature of bit-flip channels results in exponential dampening of state amplitudes, and thus observables, which does not affect the structures of interest. This is especially important as it demonstrates that the gauge theory can be successfully studied with devices that only exhibit approximate gauge invariance.