Uncloneable encryption from decoupling

Nature Physics (2026)Cite this article The laws of quantum physics mean that prominent classical cryptographic protocols can be broken using quantum computers, but they also permit security guarantees that are classically impossible. For example, quantum states cannot be cloned, which restricts the capabilities of any adversary. Here we show that uncloneable encryption exists with no computational assumptions, with security approaching the ideal value as an inverse-polynomial function of the security parameter. With this scheme, two non-interacting adversaries cannot both learn an encrypted message, even if they are both given the encryption key. Our proof uses the properties of a monogamy-of-entanglement game associated with the Haar measure encryption. Using this connection, we show that any state that succeeds with high probability cannot be close to being maximally entangled between the referee and either of the adversaries. 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