Coherent-Classical Estimation for Quantum Linear Systems

TL;DR

This paper proposes a hybrid quantum-classical estimation method for linear quantum systems, utilizing coherent feedback to improve estimation accuracy, demonstrated through an optical squeezer example.

Contribution

It introduces a novel coherent-classical estimation framework for quantum systems, incorporating coherent feedback, which has not been extensively explored before.

Findings

Coherent-classical estimators can effectively estimate quantum system variables.

Inclusion of coherent feedback enhances estimation performance.

The approach is validated with an optical squeezer example.

Abstract

This paper introduces a problem of coherent-classical estimation for a class of linear quantum systems. In this problem, the estimator is a mixed quantum-classical system which produces a classical estimate of a system variable. The coherent-classical estimator may also involve coherent feedback. An example involving optical squeezers is given to illustrate the efficacy of this idea.