23

14

What exactly is an "*oracle*"? Wikipedia says that an oracle is a "*blackbox*", but I'm not sure what that means.

For example, in the Deutsch–Jozsa algorithm,

$\hspace{85px}$,

is the oracle just the box labeled $`` U_f " ,$ or is it everything between the measurement and the inputs (including the Hadamard gates)?

And to give the oracle, do I need to write $U_f$ in matrix form or the condensed form: $U_f$ gives $y \rightarrow y \oplus f(x)$ and $x \rightarrow x$ is enough with respect to the definition of an oracle?

Microsoft has nice documentation on quantum oracles.

– Sanchayan Dutta – 2019-03-27T22:27:59.543