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arXiv 2104.02064quant-phcond-mat.stat-mech
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经典物理中的不相容可观测量:对哈密顿力学中测量的深入探讨

Incompatible observables in classical physics: A closer look at measurement in Hamiltonian mechanics

David Theurel

AI总结:

本文通过将经典哈密顿物理中的测量视为客体与有限温度仪器的联合演化,发现类似海森堡的精度-扰动关系,揭示不相容性可能也是经典物理的特征。

摘要:

量子理论著名地包含了不相容测量的存在;即成对的可观测量无法同时被测量到任意精度。不相容性被广泛认为是独特的量子现象,与量子算符的不对易性有关。尽管量子对易子和经典 Poisson 括号之间存在深刻相似性,但尚未建立 Poisson 代数与经典测量任何内在限制之间的联系。在此,我将经典 Hamilton 物理中的测量视为涉及客体系统和有限温度测量仪器的联合演化过程。我发现,与能够提取信息而不扰动系统的理想测量不同,存在类似 Heisenberg 的精度-扰动关系:测量一个可观测量使所有 Poisson 对易的可观测量保持不受扰动,但不可避免地扰动所有非 Poisson 对易的可观测量。在此关系中,h-bar 的角色由仪器特定量 q-bar 扮演。q-bar 虽非普适常数,但对于任何可建造的仪器取有限正值。我证明 Ozawa 量子测量模型的经典版本(最初提出用于违反 Heisenberg 关系)并不违反这一经典关系。因此,不相容性可能不仅是量子物理的特征,也是经典物理的特征。该方法为研究经典物理的贝叶斯认识论指明了方向,此前该领域被认为平凡。现在看来它可能非平凡且与量子形式主义相似。这些发现可能对从事量子力学基础(特别是 psi-epistemic 解释)的研究者有重要意义,并可能在精密测量、纳米工程和分子机器领域有应用。

英文摘要:

Quantum theory famously entails the existence of incompatible measurements; pairs of observables which cannot be simultaneously measured to arbitrary precision. Incompatibility is widely regarded to be a uniquely quantum phenomenon, linked to failure to commute of quantum operators. Even in the face of deep parallels between quantum commutators and classical Poisson brackets, no connection has been established between the Poisson algebra and any intrinsic limitations to classical measurement. Here I examine measurement in classical Hamiltonian physics as a process involving the joint evolution of an object-system and a finite-temperature measuring apparatus. Instead of the ideal measurement capable of extracting information without disturbing the system, I find a Heisenberg-like precision-disturbance relation: Measuring an observable leaves all Poisson-commuting observables undisturbed but inevitably disturbs all non-Poisson-commuting observables. In this relation the role of h-bar is played by an apparatus-specific quantity, q-bar. While not a universal constant, q-bar takes a finite positive value for any apparatus that can be built. I show that a classical version of Ozawa's model of quantum measurement, originally proposed as a means to violate the Heisenberg relation, does not violate the classical relation. Hence, incompatibility may prove to be a feature not only of quantum, but of classical physics too. This approach points the way to studying the Bayesian epistemology of classical physics, which was until now assumed to be trivial. It now seems possible that it is non-trivial and bears a resemblance to the quantum formalism. These findings may be of interest to researchers working on foundations of quantum mechanics, particularly for psi-epistemic interpretations. And there may be applications in the fields of precision measurement, nanoengineering and molecular machines.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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