2020/05/24 by Dov Fields, Fields, Dov, Árpád Varga +3
Computer Science · Physics and Astronomy · #81P15 (Primary) #81P45 (Secondary) #FOS: Physical sciences #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum Physics (quant-ph)
paper · pdf · doi:10.48550/arxiv.2005.11656
openalex publication_date 2020/05/24 · openalex created_date 2022/07/26 · openalex updated_date 2026/07/28
We study sequential state discrimination measurements performed on the same\nqubit by subsequent observers. Specifically, we focus on the case when the\nobservers perform a kind of a minimum-error type state discriminating\nmeasurement where the goal of the observers is to maximize their joint\nprobability of successfully guessing the state that the qubit was initially\nprepared in. We call this the joint best guess strategy. In this scheme, Alice\nprepares a qubit in one of two possible states. The qubit is first sent to Bob,\nwho measures it, and then on to Charlie, and so on to altogether N consecutive\nreceivers who all perform measurements on it. The goal for all observers is to\ndetermine which state Alice sent. In the joint best guess strategy, every time\na system is received the observer is required to make a guess, aided by the\nmeasurement, about its state. The price to pay for this requirement is that\nerrors must be permitted, the guess can be correct or in error. There is a\nnonzero probability for all the receivers to successfully identify the\ninitially prepared state, and we maximize this joint probability of success.\nThis work is a step toward developing a theory of nondestructive sequential\nquantum measurements and could be useful in multiparty quantum communication\nschemes based on communicating with single qubits, particularly in schemes\nemploying continuous variable states. It also represents a case where\nsubsequent observers can probabilistically and optimally get around both the\ncollapse postulate and the no-broadcasting theorem.\n