Signatures of Open and Noisy Quantum Systems in Single-Qubit Quantum Annealing

TL;DR

This paper introduces a quantum annealing protocol that uses D-Wave's h-gain schedule to distinguish open and closed system dynamics and identify noise sources in single-qubit hardware.

Contribution

It presents a novel protocol leveraging D-Wave's h-gain schedule to probe qubit dynamics and noise effects more effectively than previous methods.

Findings

Thermal and magnetic field fluctuations significantly affect qubit behavior.

The proposed protocol can differentiate between open and closed system dynamics.

Including noise sources in models is essential to match hardware output statistics.

Abstract

We propose a quantum annealing protocol that more effectively probes the dynamics of a single qubit on D-Wave's quantum annealing hardware. This protocol uses D-Wave's h-gain schedule functionality, which allows the rapid quenching of the longitudinal magnetic field at arbitrary points during the anneal. This features enables us to distinguish between open and closed system dynamics as well as the presence or absence of longitudinal magnetic field noise. We show that both thermal and magnetic field fluctuations are key sources of noise that need to be included in an open quantum system model to reproduce the output statistics of the hardware.