Question

Category-theoretic versions of this theorem and its dual state that a tensor product in a monoidal category lacks a natural diagonal and projection, respectively. Stephen Wiesner proposed a wacky scheme for money in which this theorem ensures that banknotes are difficult to forge. A generalization of this theorem (15[1])surprisingly doesn’t apply to more than one input due to a technique called “superbroadcasting”. In the BB84 key distribution protocol, this theorem implies that the private key is safe from eavesdropping with high probability. Designs of quantum error correcting codes must work around the restrictions (-5[1])implied by this theorem to achieve (*) redundancy. This theorem was proven by Wootters and Zurek while rebutting the possibility of faster-than-light communication using quantum entanglement. (10[1])For 10 (-5[1])points, name this theorem that prohibits direct copying of pure quantum states. ■END■ (10[3])

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