A Reduced Order Direct Coupling Coherent Quantum Observer for a Complex Quantum Plant

TL;DR

This paper develops a reduced order direct coupling quantum observer for complex quantum harmonic oscillator networks, enabling efficient estimation of multiple variables with an observer of minimal size.

Contribution

It introduces a novel reduced order observer design for complex quantum systems, extending previous work to larger, networked quantum harmonic oscillators.

Findings

Observer order can match the number of estimated variables when even

Conditions for the existence of such observers are established

The approach enhances efficiency in quantum system monitoring

Abstract

This paper extends previous results on constructing a direct coupling quantum observer for a quantum harmonic oscillator system. In this case, we consider a complex linear quantum system plant consisting of a network of quantum harmonic oscillators. Conditions are given for which there exists a direct coupling observer which estimates a collection of variables in the quantum plant. It is shown that the order of the observer can be the same as the number of variables to be estimated when this number is even and thus this is a reduced order observer.