Robust $H_\infty$ Coherent-Classical Estimation of Linear Quantum Systems

TL;DR

This paper develops a robust $H_$ coherent-classical estimation method for linear quantum systems with uncertainties, demonstrating improved disturbance rejection and robustness over classical estimators, especially with coherent feedback.

Contribution

It introduces a novel robust estimation approach combining coherent and classical techniques for uncertain quantum systems, enhancing performance and robustness.

Findings

Robust $H_$ estimators outperform classical ones in uncertain quantum systems.

Coherent feedback improves robustness against parameter uncertainties.

The proposed method achieves better disturbance-to-error performance.

Abstract

We study robust $H_\infty$ coherent-classical estimation for a class of physically realizable linear quantum systems with parameter uncertainties. Such a robust coherent-classical estimator, with or without coherent feedback, can yield better disturbance-to-error performance than the corresponding robust purely-classical estimator for an uncertain plant. Moreover, coherent feedback allows for such a robust coherent-classical estimator to be more robust to uncertainty in comparison to the robust classical-only estimator.