Black holes are believed to be fast scramblers of information, as they rapidly destroy local correlations and spread information throughout the system. Unscrambling this information is in principle possible, given perfect knowledge of the black hole internal dynamics[arXiv:1710.03363]. This work shows that even if one doesn't know the internal dynamics of the black hole, information can be efficiently decoded from an unknown black hole by observing the outgoing Hawking radiation. We show that, surprisingly, black holes with an unknown internal dynamics that are rapidly scrambling but not fully chaotic admit Clifford decoders: the salient properties of a scrambling unitary can be efficiently recovered even if exponentially complex. This recovery is possible because all the redundant complexity can be described as an entropy, the stabilizer entropy. We show how for non-chaotic black holes the stabilizer entropy can be efficiently pumped away, just as in a refrigerator.

翻译：黑洞被认为是信息的快速搅乱者，它们迅速破坏局域关联并将信息扩散至整个系统。原则上，若完全掌握黑洞内部动力学，即可解扰这些信息[arXiv:1710.03363]。本研究表明，即便不了解黑洞内部动力学，通过观测霍金辐射也能从未知黑洞中高效解码信息。令人惊讶的是，我们证明具有未知内部动力学但快速搅乱（尚未达到完全混沌状态）的黑洞允许使用克利福德译码器：即使指数级复杂的搅乱幺正算符，其显著特性也能被高效恢复。这种恢复之所以可行，是因为所有冗余复杂性均可描述为一种熵——稳定子熵。我们展示了对于非混沌黑洞，如何像制冷机一样高效泵除稳定子熵。