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arXiv 0905.4398quant-phmath-phmath.MPphysics.gen-ph
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冯·诺依曼和吕德斯假设与量子信息理论

Von Neumann and Luders postulates and quantum information theory

Andrei Khrennikov

摘要:

本文介绍了与量子信息理论有关的量子力学的一些基本问题,特别是量子隐形传态和单向量子计算。“我们强调了投射假设(决定测量后的状态)在QI中的作用,以及它的吕德斯和冯诺依曼版本之间的差异。这些投影假设在具有简并光谱的观测量的情况下有着关键的不同。这样的观测量在纠缠态的操作中起着重要的作用:一个子系统上的任何测量都由复合系统的希尔伯特空间中具有简并谱的观测量表示。如果冯·诺依曼是对的,而吕德斯是错的,那么量子隐形传态和“单向量子计算”的规范方案就不会起作用。令人惊讶的是,我们发现,事实上,冯·诺依曼通过细化测量的描述意味着(在自然假设下)吕德斯投影假设。在过去的70年里,这一重要的观察似乎被忽略了。这一结果解决了在量子信息理论中正确使用投影公设的问题。人们可以继续使用吕德斯假设(就像量子信息领域的人们所做的那样)。

英文摘要:

This note is devoted to some foundational aspects of quantum mechanics (QM) related to quantum information (QI) theory, especially quantum teleportation and ``one way quantum computing.'' We emphasize the role of the projection postulate (determining post-measurement states) in QI and the difference between its Lüders and von Neumann versions. These projection postulates differ crucially in the case of observables with degenerate spectra. Such observables play the fundamental role in operations with entangled states: any measurement on one subsystem is represented by an observable with degenerate spectrum in the Hilbert space of a composite system. If von Neumann was right and Lüders was wrong the canonical schemes of quantum teleportation and ``one way quantum computing'' would not work. Surprisingly, we found that, in fact, von Neumann's description of measurements via refinement implies (under natural assumptions) Lüders projection postulate. It seems that this important observation was missed during last 70 years. This result closed the problem of the proper use of the projection postulate in quantum information theory. One can proceed with Lüders postulate (as people in quantum information really do).

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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