Minimizing back-action through entangled measurements

• Published in: arXiv.org
• Main Authors: Kang-Da, Wu, Bäumer, Elisa, Jun-Feng, Tang, Hovhannisyan, Karen V, Perarnau-Llobet, Martí, Guo-Yong, Xiang, Chuan-Feng, Li, Guo, Guang-Can
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 18.11.2020
• Subjects: Entanglement; Physics - Quantum Physics; Quantum theory
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2011.09100

When an observable is measured on an evolving coherent quantum system twice, the first measurement generally alters the statistics of the second one, which is known as measurement back-action. We introduce, and push to its theoretical and experimental limits, a novel method of back-action evasion, whereby entangled collective measurements are performed on several copies of the system. This method is inspired by a similar idea designed for the problem of measuring quantum work [Perarnau-Llobet \textit{et al}., (https://doi.org/10.1103/PhysRevLett.118.070601) Phys. Rev. Lett. \textbf{118}, 070601 (2017)]. By utilizing entanglement as a resource, we show that the back-action can be extremely suppressed compared to all previous schemes. Importantly, the back-action can be eliminated in highly coherent processes.