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Quantum cloning with nonlocal assistance: Complement of Jozsa's stronger no-cloning theorem

Koji Azuma·Masato Koashi·Hosho Katsura·Nobuyuki Imoto
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Abstract

We investigate the cases where a set $S$ of states $\{\ket{ψ_i} \}$ cannot be cloned by itself, but is clonable with the help of another system prepared in state $\hatρ_i$. When $S$ is pair-wise nonorthogonal, it is known that one can generate the copy from $\hatρ_i$ alone, with no interaction with the original system. Here we show that a set containing orthogonal pairs exhibits a property forming a striking contrast; For any such set, there is a choice of $\hatρ_i$ that enables cloning only when the two systems are interacted in a purely quantum manner that is not achievable via classical communication.

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Koji Azuma, Masato Koashi, Hosho Katsura, Nobuyuki Imoto. 2006-04-03. Quantum cloning with nonlocal assistance: Complement of Jozsa's stronger no-cloning theorem. https://arxiv.org/abs/quant-ph/0604009

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