No-deleting principle for two unitary copies

Dafa Li

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arXiv · 2606.24522

No-deleting principle for two unitary copies

Dafa Li

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Abstract

Pati and Braunstein defined a deleting machine and showed the impossibility of deleting one of two identical copies of an unknown quantum state. So far, no one has defined two non-identical copies of a quantum state, of course no one has discussed the impossibility of deleting one of two non-identical copies of an unknown quantum state. In this paper, we define $u|{\psi}>$ and $U|{\psi}>$, where $u$ and $U$ are any unitary operators, as two unitary copies of a quantum state $|{\psi}>$, and show that it is impossible to delete one of two unitary copies of an unknown state.

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Dafa Li. 2026-06-23. No-deleting principle for two unitary copies. https://arxiv.org/abs/2606.24522

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