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No-cloning of Orthogonal States in Composite Systems

Tal Mor
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Abstract

The no-cloning principle tells us that non-orthogonal quantum states cannot be cloned, but it does not tell us that orthogonal states can always be cloned. We suggest a situation where the cloning transformations are restricted, leading to a novel type of no-cloning principle. In the case of a composite system made of two subsystems: if the subsystems are only available one after the other then there are various cases when orthogonal states cannot be cloned. Surprising examples are given, which give a radically better insight regarding the basic concepts of quantum cryptography.

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Tal Mor. 1998-02-12. No-cloning of Orthogonal States in Composite Systems. https://doi.org/10.1103/physrevlett.80.3137

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