Linear quantum systems: poles, zeros, invertibility and sensitivity

Fuente: arXiv
Saved in:
Bibliographic Details
Main Authors: Dong, Zhiyuan, Zhang, Guofeng, Lee, Heung-wing Joseph, Petersen, Ian R.
Format: Preprint
Published: 2024
Subjects:
Online Access:
Tags: Add Tag
No Tags, Be the first to tag this record!
_version_ 1866916970959470592
author Dong, Zhiyuan
Zhang, Guofeng
Lee, Heung-wing Joseph
Petersen, Ian R.
author_facet Dong, Zhiyuan
Zhang, Guofeng
Lee, Heung-wing Joseph
Petersen, Ian R.
contents The non-commutative nature of quantum mechanics imposes fundamental constraints on system dynamics, which, in the linear realm, are manifested through the physical realizability conditions on system matrices. These restrictions give system matrices a unique structure. This paper aims to study this structure by investigating the zeros and poles of linear quantum systems. Firstly, it is shown that $-s_0$ is a transmission zero if and only if $s_0$ is a pole of the transfer function, and $-s_0$ is an invariant zero if and only if $s_0$ is an eigenvalue of the $A$-matrix, of a linear quantum system. Moreover, $s_0$ is an output-decoupling zero if and only if $-s_0$ is an input-decoupling zero. Secondly, based on these pole-zero correspondences and inspired by a recent work on the stable inversion of classical linear systems \cite{DD2023}, we show that a linear quantum system must be Hurwitz unstable if it is strongly asymptotically left invertible. Two types of stable input observers are constructed for unstable linear quantum systems. Finally, the sensitivity of a coherent feedback network is investigated; in particular, the fundamental tradeoff between ideal squeezing and system robustness is studied on the basis of system sensitivity analysis.
format Preprint
id arxiv_https___arxiv_org_abs_2410_00014
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Linear quantum systems: poles, zeros, invertibility and sensitivity
Dong, Zhiyuan
Zhang, Guofeng
Lee, Heung-wing Joseph
Petersen, Ian R.
Quantum Physics
The non-commutative nature of quantum mechanics imposes fundamental constraints on system dynamics, which, in the linear realm, are manifested through the physical realizability conditions on system matrices. These restrictions give system matrices a unique structure. This paper aims to study this structure by investigating the zeros and poles of linear quantum systems. Firstly, it is shown that $-s_0$ is a transmission zero if and only if $s_0$ is a pole of the transfer function, and $-s_0$ is an invariant zero if and only if $s_0$ is an eigenvalue of the $A$-matrix, of a linear quantum system. Moreover, $s_0$ is an output-decoupling zero if and only if $-s_0$ is an input-decoupling zero. Secondly, based on these pole-zero correspondences and inspired by a recent work on the stable inversion of classical linear systems \cite{DD2023}, we show that a linear quantum system must be Hurwitz unstable if it is strongly asymptotically left invertible. Two types of stable input observers are constructed for unstable linear quantum systems. Finally, the sensitivity of a coherent feedback network is investigated; in particular, the fundamental tradeoff between ideal squeezing and system robustness is studied on the basis of system sensitivity analysis.
title Linear quantum systems: poles, zeros, invertibility and sensitivity
topic Quantum Physics
url https://arxiv.org/abs/2410.00014