Lee Ciarán M, Selby John H
Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK.
Department of Computer Science, University of Oxford, Oxford OX1 3QD, UK.
Proc Math Phys Eng Sci. 2018 Jun;474(2214):20170732. doi: 10.1098/rspa.2017.0732. Epub 2018 Jun 27.
To date, there has been no experimental evidence that invalidates quantum theory. Yet it may only be an effective description of the world, in the same way that classical physics is an effective description of the quantum world. We ask whether there exists an operationally defined theory superseding quantum theory, but which reduces to it via a decoherence-like mechanism. We prove that no such post-quantum theory exists if it is demanded that it satisfy two natural physical principles: and . Causality formalizes the statement that information propagates from present to future, and purification that each state of incomplete information arises in an essentially unique way due to lack of information about an environment. Hence, our result can be viewed either as evidence that the fundamental theory of Nature is quantum or as showing in a rigorous manner that any post-quantum theory must abandon causality, purification or both.
迄今为止，尚无实验证据能证伪量子理论。然而，它可能只是对世界的一种有效描述，就如同经典物理学是对量子世界的有效描述一样。我们要问，是否存在一种通过类似退相干机制简化为量子理论，但在操作上定义的超越量子理论的理论。我们证明，如果要求这种后量子理论满足两个自然物理原理：因果性和纯化，那么不存在这样的理论。因果性将信息从现在传播到未来这一陈述形式化，而纯化则表明，由于缺乏关于环境的信息，每个不完全信息状态本质上以一种独特的方式产生。因此，我们的结果既可以被视为自然的基本理论是量子理论的证据，也可以被视为以一种严谨的方式表明，任何后量子理论都必须放弃因果性、纯化或两者。
