Hurst Hilary M, Spielman I B
Joint Quantum Institute, National Institute of Standards and Technology, and University of Maryland, Gaithersburg, Maryland 20899, USA.
Phys Rev A (Coll Park). 2019;99(5). doi: 10.1103/physreva.99.053612.
Weakly measuring many-body systems and allowing for feedback in real time can simultaneously create and measure new phenomena in quantum systems. We theoretically study the dynamics of a continuously measured two-component Bose-Einstein condensate (BEC) potentially containing a domain wall and focus on the tradeoff between usable information obtained from measurement and quantum backaction. Each weakly measured system yields a measurement record from which we extract real-time dynamics of the domain wall. We show that quantum backaction due to measurement causes two primary effects: domain-wall diffusion and overall heating. The system dynamics and signal-to-noise ratio depend on the choice of measurement observable. We propose a feedback protocol to dynamically create a stable domain wall in the regime where domain walls are unstable, giving a prototype example of Hamiltonian engineering using measurement and feedback.
对多体系统进行弱测量并实时引入反馈，可以同时在量子系统中创造和测量新现象。我们从理论上研究了一个连续测量的双分量玻色-爱因斯坦凝聚体（BEC）的动力学，该凝聚体可能包含一个畴壁，并着重探讨从测量中获得的可用信息与量子反作用之间的权衡。每个弱测量系统都会产生一个测量记录，我们从中提取畴壁的实时动力学。我们表明，测量引起的量子反作用会产生两个主要效应：畴壁扩散和整体加热。系统动力学和信噪比取决于测量可观测量的选择。我们提出了一种反馈协议，用于在畴壁不稳定的 regime 中动态创建稳定的畴壁，给出了一个使用测量和反馈进行哈密顿量工程的原型示例。 （注：“regime”此处可能需要结合上下文更准确地翻译，比如“状态”“条件”等，这里直接保留英文是因为原文未明确合适的中文表述）
