Wu Kang-Da, Bäumer Elisa, Tang Jun-Feng, Hovhannisyan Karen V, Perarnau-Llobet Martí, Xiang Guo-Yong, Li Chuan-Feng, Guo Guang-Can
CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People's Republic of China.
CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China.
Phys Rev Lett. 2020 Nov 20;125(21):210401. doi: 10.1103/PhysRevLett.125.210401.
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 backaction. We introduce, and push to its theoretical and experimental limits, a novel method of backaction 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 et al., Phys. Rev. Lett. 118, 070601 (2017)PRLTAO0031-900710.1103/PhysRevLett.118.070601]. By using entanglement as a resource, we show that the backaction can be extremely suppressed compared to all previous schemes. Importantly, the backaction can be eliminated in highly coherent processes.
当在一个不断演化的相干量子系统上对一个可观测量进行两次测量时，第一次测量通常会改变第二次测量的统计结果，这被称为测量反作用。我们引入了一种新颖的反作用规避方法，并将其推到理论和实验极限，即对系统的多个副本进行纠缠集体测量。该方法受到为测量量子功问题设计的类似想法的启发[佩拉诺 - 洛贝等人，《物理评论快报》118, 070601 (2017)PRLTAO0031 - 900710.1103/PhysRevLett.118.070601]。通过将纠缠用作一种资源，我们表明与所有先前的方案相比，反作用可以被极大地抑制。重要的是，在高度相干的过程中反作用可以被消除。
