开放系统动力学下的被动实在论
Passive realism in the presence of open system dynamics
- Hainan University（海南大学）
- Hainan International Exchange Center for Theoretical Physics（海南理论物理交流中心）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文提出被动实在论概念，证明在开放系统动力学下，除非初始态最大混合或信道为丢弃-制备型，否则必然存在违反NSIT的测量，表明环境无法完全抹去测量痕迹。
AI中文摘要：
我们引入术语“被动实在论”来概括一种与尺度无关的假设，即物理系统预先存在的属性可以被被动地观测，而不会改变其后续动力学。被动实在论的一个必要条件是时间无信号（NSIT）条件，该条件指出，测量结果与是否执行了先前测量无关。由于测量反作用，封闭量子系统通常会违反NSIT，但我们研究开放系统动力学是否能将这种干扰耗散到环境中并恢复NSIT。通过将连续测量之间的时间演化建模为任意量子信道，我们表明这种环境掩蔽仅在两种特殊情况下可能。具体而言，我们证明，如果两次连续测量场景的初始状态不是最大混合态，并且控制测量之间动力学的信道不是丢弃-制备信道，那么必然存在违反NSIT的二元投影测量，从而违反被动实在论。通过提供确定这些违反测量的构造性程序——此处应用于退极化和退相位信道——我们证明，在这两种情况之外，系统-环境相互作用无法为所有测量选择抹去量子测量的统计足迹。
英文摘要：
We introduce the terminology \emph{passive realism} to encapsulate the scale-independent assumption that a physical system's pre-existing properties can be passively observed without altering its subsequent dynamics. A necessary condition for passive realism is provided by the no-signalling in time (NSIT) condition, which states that a measurement outcome is independent of whether or not a prior measurement was performed. While closed quantum systems generically violate NSIT due to measurement back action, we investigate whether open-system dynamics can dissipate this disturbance to the environment and restore NSIT. By modeling the time evolution between sequential measurements as an arbitrary quantum channel, we show that such environmental masking is possible only in two special cases. Specifically, we show that if the initial state of a two-time sequential measurement scenario is not maximally mixed, and if the channel governing the dynamics between measurements is not a discard-and-prepare channel, then there necessarily exist binary projective measurements violating NSIT, hence violating passive realism. By providing a constructive procedure for determining these violating measurements---applied here to depolarizing and dephasing channels---we demonstrate that, outside these two cases, system-environment interactions cannot erase the statistical footprint of a quantum measurement for all measurement choices.
