Andrew M. Childs

On State Distinguishing Without Inverse Queries

In the quantum state distinguishing problem, an algorithm is given copies of a state $|\psi\rangle$ or $|\phi\rangle$ separated by trace distance $\varepsilon$, and tasked with deciding which is the case. It is a standard result that $\Theta(\varepsilon^{-2})$ copies are required, while having access to a unitary state...