Bound on the number of functions that can be distinguished with k quantum queries
Edward Farhi, Jeffrey Goldstone, Sam Gutmann, Michael Sipser · Physical Review A · 1999
Suppose an oracle is known to hold one of a given set of D two-valued functions. To successfully identify which function the oracle holds with k classical queries, it must be the case that D is at most ${2}^{k}.$ In this paper we derive a bound for how many functions can be distinguished with k quantum queries.