In this theorem we have a unitary transformation ##U|a>|b>=|a>|a>##(adsbygoogle = window.adsbygoogle || []).push({});

But isnt it obvious that this is a rotation on a subspace but this rotation should depend on both |a> and |b> ?

With this dependence it seems to me the conclusion cannot be reached since the unitarity is U(a,b)U(a,b)^+=1 but U(c,b)U(a,b)^+ is not forcedly 1.

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# Question about the no-cloning theorem

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