I am having trouble understanding the following:(adsbygoogle = window.adsbygoogle || []).push({});

U_{f}: |x>|y> → |x>|y [itex]\oplus[/itex]f(x)>

[itex]\oplus[/itex] being a mod 2 operation (nand)? I suppose I don't understand how to read the "ket" states so well. As far as I understand we have that since x and y can be 0,1 only if |x=1>|y=1> then if f(x) = 1 then |y [itex]\oplus[/itex] f(x)> would come out to be → |1>|0>

but the main part is that if we are dealing with a quantum computer then we can chose the input state to the a superposition of |0> and |1>. That if the second qubit is initially prepared in the state 1/[itex]\sqrt{2}[/itex](|0> - |1> then... The issue is with this equation in that how does |0> - |1> mean superposition? This is the part of the bra-ket notation that I don't understand

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# Bra-ket notation and qubit issue.

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