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On the non-existence of a universal Hadamard gate

Preeti Parashar
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Abstract

We establish the non-existence of a universal Hadamard gate for arbitrary unknown qubits, by considering two different principles; namely, no-superluminal signalling and non-increase of entanglement under LOCC. It is also shown that these principles are not violated if and only if the qubit states are of a special form obtained in our recent work [ IJQI (in press), quant-ph/0505068 ].

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Preeti Parashar. 2006-06-28. On the non-existence of a universal Hadamard gate. https://arxiv.org/abs/quant-ph/0606231

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