Multiparty quantum state discrimination

Abstract

We consider the problem of identifying an unknown multiparty quantum state using local operations and classical communication (LOCC). In particular, we consider a class of protocols that utilize a sequence of LOCC, referred to as LOCC protocols. We derive the necessary and sufficient conditions for optimal LOCC protocol that maximizes the probability of correct identification (PCI) and provide an algorithm to determine the maximal PCI. Moreover, we develop a protocol based on the alternating optimization approach and demonstrate its near-optimal performance. The numerical results suggest that the LOCC protocols can be desirable alternatives to traditional discrimination approaches that require measuring the entire state of a quantum system.