Online strategies for exactly identifying a quantum change point

Gael Sentís*, Esteban Martínez-Vargas, Ramon Muñoz-Tapia

*Corresponding author for this work

Research output: Contribution to journalArticleResearch

4 Citations (Scopus)


We consider online detection strategies for identifying a change point in a stream of quantum particles allegedly prepared in identical states. We show that the identification of the change point can be done without error via sequential local measurements while attaining the optimal performance bound set by quantum mechanics. In this way, we establish the task of exactly identifying a quantum change point as an instance where local protocols are as powerful as global ones. The optimal online detection strategy requires only one bit of memory between subsequent measurements, and it is amenable to experimental realization with current technology.

Original languageEnglish
Article number052305
JournalPhysical Review A
Issue number5
Publication statusPublished - 5 Nov 2018


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