旧瓶装新酒：量子测量--直接、间接、弱--及其应用
New wine in old bottles: Quantum measurement - direct, indirect, weak - with some applications
摘要：
在这部分教学审查，我试图给一个独立的概述（非相对论）QM测量理论的基础上表示的密度矩阵形式主义。重点是弱测量理论的应用，由Aharonov和Vaidman及其合作者开发。他们的弱测量发展结合了他们所谓的“后选择”-明智地选择不仅是系统的初始状态（“预选”），而且是其最终状态-最近受到了很多关注。尤其是它开辟了新的、富有成效的实验前景，比如新的放大方法。但这种做法也给它带来了一些神秘的气氛。我将试图通过展示（几乎）所有的结果都可以直接从传统的QM中得出来“去神秘化”它。除其他事项外，我发展的形式主义，不仅一阶，而且二阶的弱相互作用负责测量。这也使我能够导出，或多或少作为副产品，一个开放系统的密度矩阵与环境相互作用的主方程。一个特殊的应用，我将处理的弱测量是所谓的Leggett-Garg不等式，又称为“贝尔不等式在时间”。我也给了一个大纲，即使是粗略的，一些巧妙的实验，由阿哈罗诺夫，Vaidman和合作者的工作已经启发。如果说弱测量+后选择方法中有什么神奇之处，那就是对所谓的可观测值的弱值的解释。它是否是所考虑的系统的善意财产？我无法回答这个问题;我只会提出建议解释的利弊。
英文摘要：
In this, partly pedagogical review, I attempt to give a self-contained overview of the basis of (non-relativistic) QM measurement theory expressed in density matrix formalism. The focus is on applications to the theory of weak measurement, as developed by Aharonov and Vaidman and their collaborators. Their development of weak measurement combined with what they call 'post-selection' - judiciously choosing not only the initial state of a system ('pre-selection') but also its final state - has received much attention recently. Not the least has it opened up new, fruitful experimental vistas, like novel approaches to amplification. But the approach has also attached to it some air of mystery. I will attempt to 'de-mystify' it by showing that (almost) all results can be derived in a straight-forward way from conventional QM. Among other things, I develop the formalism not only to first order but also to second order in the weak interaction responsible for the measurement. This also allows me to derive, more or less as a by-product, the master equation for the density matrix of an open system in interaction with an environment. One particular application I shall treat of the weak measurement is the so called Leggett-Garg inequalities, a k a 'Bell inequalities in time'. I also give an outline, even if rough, of some of the ingenious experiments that the work by Aharonov, Vaidman and collaborators has inspired. If anything is magic in the weak measurement + post-selection approach, it is the interpretation of the so called weak value of an observable. Is it a bona fide property of the system considered? I have no answer to this question; I shall only exhibit the pros and cons of the proposed interpretation.
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。
