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Main Authors: Dong, Zhiyuan, Liang, Weichao, Zhang, Guofeng
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.11507
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author Dong, Zhiyuan
Liang, Weichao
Zhang, Guofeng
author_facet Dong, Zhiyuan
Liang, Weichao
Zhang, Guofeng
contents We establish a framework for realizing back-action-evading (BAE) measurements and quantum non-demolition (QND) variables in linear quantum systems. The key condition, a purely imaginary Hamiltonian with a real or imaginary coupling operator, enables BAE measurements of conjugate observables. Symmetric coupling further yields QND variables. For non-compliant systems, coherent feedback can engineer BAE measurements. Crucially, the QND interaction condition simultaneously ensures BAE measurements and promotes the coupling operator to a QND observable. This work provides a unified structural theory for enhancing precision in quantum metrology and sensing.
format Preprint
id arxiv_https___arxiv_org_abs_2603_11507
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Back-Action-Evading Measurements and Quantum Non-Demolition Variables via Linear Systems Engineering
Dong, Zhiyuan
Liang, Weichao
Zhang, Guofeng
Quantum Physics
We establish a framework for realizing back-action-evading (BAE) measurements and quantum non-demolition (QND) variables in linear quantum systems. The key condition, a purely imaginary Hamiltonian with a real or imaginary coupling operator, enables BAE measurements of conjugate observables. Symmetric coupling further yields QND variables. For non-compliant systems, coherent feedback can engineer BAE measurements. Crucially, the QND interaction condition simultaneously ensures BAE measurements and promotes the coupling operator to a QND observable. This work provides a unified structural theory for enhancing precision in quantum metrology and sensing.
title Back-Action-Evading Measurements and Quantum Non-Demolition Variables via Linear Systems Engineering
topic Quantum Physics
url https://arxiv.org/abs/2603.11507