Improved quantum test for linearity of a Boolean function

Abstract

Let a Boolean function be available as a black-box (oracle) and one likes to devise an algorithm to test whether it has certain property or it is $\epsilon$-far from having that property. The efficiency of the algorithm is judged by the number of calls to the oracle so that one can decide, with high probability, between these two alternatives. The best known quantum algorithm for testing whether a function is linear or $\epsilon$-far $(0 < \epsilon < \frac{1}{2})$ from linear functions requires $O(\epsilon^{-\frac{2}{3}})$ many calls [Hillery and Andersson, Physical Review A 84, 062329 (2011)]. We show that this can be improved to $O(\epsilon^{-\frac{1}{2}})$ by using the Deutsch-Jozsa and the Grover Algorithms.