论文标题
统一的量子理论不能一致地描述自身的使用：在Frauchiger-Renner悖论上
Unitary-Only Quantum Theory Cannot Consistently Describe the Use of Itself: On the Frauchiger-Renner Paradox
论文作者
论文摘要
Frauchiger-Renner悖论是基于“测量问题”的悖论的扩展，例如Schrodinger的Cat和Wigner的朋友。所有这些悖论都源于假设量子理论仅具有统一的（线性）物理动力学，以及关于什么是“测量”的歧义，即无法说明从理论本身内部观察到确定测量结果的观察。本文讨论了在FR场景中的基本不一致时，比派生的矛盾要早得多：即，将不当混合物（降低密度操作员）作为合适的认知混合物固有的不一致。如果假定量子理论始终是统一的，这是一个非法的程序。相比之下，在对量子降低产量确定结果的非独立描述下，使用适当的混合物进行测量结果变得合理，并且整个悖论都无法安装。结论是，FR悖论的真正教训是，需要重新评估的是单一的仅假设。
The Frauchiger-Renner Paradox is an extension of paradoxes based on the 'Problem of Measurement,' such as Schrodinger's Cat and Wigner's Friend. All of these paradoxes stem from assuming that quantum theory has only unitary (linear) physical dynamics, and the attendant ambiguity about what counts as a 'measurement'--i.e., the inability to account for the observation of determinate measurement outcomes from within the theory itself. This paper discusses a basic inconsistency arising in the FR scenario at a much earlier point than the derived contradiction: namely, the inconsistency inherent in treating an improper mixture (reduced density operator) as a proper, epistemic mixture. This is an illegitimate procedure that is nevertheless endemic if quantum theory is assumed to be always unitary. In contrast, under a non-unitary account of quantum state reduction yielding determinate outcomes, the use of a proper mixture for measurement results becomes legitimate, and this entire class of paradoxes cannot be mounted. The conclusion is that the real lesson of the FR paradox is that it is the unitary-only assumption that needs to be critically reassessed.
