论文标题

尊重自己的家伙:QBISM对Wigner的朋友的分析

Respecting One's Fellow: QBism's Analysis of Wigner's Friend

论文作者

DeBrota, John B., Fuchs, Christopher A., Schack, Ruediger

论文摘要

根据QBISM,量子状态,单一的演变和测量操作员都被理解为使用形式主义的代理人的个人判断。同时,量子测量结果被理解为同一代理人的个人经历。威格纳(Wigner)对朋友的难题,在表面上,两个代理人对是否有测量结果有不同的说法,因此对QBISM没有任何悖论。实际上,Wigner原始思想实验的解决是Qbist思维发展的核心。本文的重点涉及对Wigner难题的两个非常有启发性的修改:一个是Frauchiger和Renner最近的无关定理,另一个是Baumann和Brukner的思想实验。我们表明,一旦朋友和威格尔都将量子理论的个人用途理解为同等基础的代理,这些作品中强调的悖论特征就消失了。从朋友的角度来看,威格纳对他的朋友的行动成为了朋友对威格纳采取的行动。我们的分析基于一种量子哥白尼原则:当两个代理相互采取行动时,每个代理都具有双重作用,作为另一个代理的物理系统。量子理论的用户没有比其他任何人更有特权。与Wigner原始论文的观点相反,在“暂停动画”中都不应将其视为。从这个角度来看,QBISM带来了一个全新的观点,可以理解Wigner的朋友思想实验。

According to QBism, quantum states, unitary evolutions, and measurement operators are all understood as personal judgments of the agent using the formalism. Meanwhile, quantum measurement outcomes are understood as the personal experiences of the same agent. Wigner's conundrum of the friend, in which two agents ostensibly have different accounts of whether or not there is a measurement outcome, thus poses no paradox for QBism. Indeed the resolution of Wigner's original thought experiment was central to the development of QBist thinking. The focus of this paper concerns two very instructive modifications to Wigner's puzzle: One, a recent no-go theorem by Frauchiger and Renner, and the other a thought experiment by Baumann and Brukner. We show that the paradoxical features emphasized in these works disappear once both friend and Wigner are understood as agents on an equal footing with regard to their individual uses of quantum theory. Wigner's action on his friend then becomes, from the friend's perspective, an action the friend takes on Wigner. Our analysis rests on a kind of quantum Copernican principle: When two agents take actions on each other, each agent has a dual role as a physical system for the other agent. No user of quantum theory is more privileged than any other. In contrast to the sentiment of Wigner's original paper, neither agent should be considered as in "suspended animation." In this light, QBism brings an entirely new perspective to understanding Wigner's friend thought experiments.

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