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 (15[1])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]-5[1])For 10 (-5[1])points, name this theorem that prohibits direct copying (10[1])of pure quantum states. ■END■ (10[5])

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