Kvantetilstander kan ikke kopieres—med mindre de er i tilstanden $|0\rangle$ eller $|1\rangle$ (noe som impliserer at klassiske tilstander *kan* kopieres). Mest kjent for å ha blitt publisert i 1982 (som en respons til en foreslått [superluminal kommunikasjonsprotokoll](https://en.wikipedia.org/wiki/No-cloning_theorem)), dog en variant av teoremet ble publisert i 1970, og Stephen Wiesner allerede implisitt tok teoremet for gitt i sin konstruksjon av [[Kvantepenger]] på sekstitallet. ### One-out-of-many [TCC:KitNis23 – One-out-of-Many Unclonable Cryptography: Definitions, Constructions, and More](https://eprint.iacr.org/2023/229) introduserte svakere definisjoner for ikke-klonbarhet, for lettere anvendelse i sikkerhetsbevis: > The no-cloning principle of quantum mechanics enables us to achieve amazing unclonable cryptographic primitives, which is impossible in classical cryptography. However, the security definitions for unclonable cryptography are tricky. Achieving desirable security notions for unclonability is a challenging task. In particular, there is no indistinguishable-secure unclonable encryption and quantum copy-protection for single-bit output point functions in the standard model. To tackle this problem, we introduce and study relaxed but meaningful security notions for unclonable cryptography in this work. We call the new security notion one-out-of-many unclonable security. > > (...) > > Thus, we obtain one-out-of-many indistinguishable-secure unclonable encryption, one-out-of-many copy-protection for single-bit output point functions, and one-out-of-many unclonable PE in the standard model from the LWE assumption.