Adaptive Generalized Measurement for Unambiguous State Discrimination of Quaternary Phase-Shift-Keying Coherent States

Generalized quantum measurements identifying nonorthogonal states without ambiguity often play an indispensable role in various applications. For such unambiguous state-discrimination scenario, we have a finite probability of obtaining inconclusive results and minimizing the is particular importance. In this paper, experimentally demonstrate adaptive generalized measurement that can unambiguously discriminate quaternary phase-shift-keying coherent with near-optimal performance. Our scheme composed displacement operations, single-photon detections control displacements dependent on history photon-detection outcomes. experimental show clear improvement both conclusive ratio erroneous decision caused by unavoidable imperfections over conventional static measurements.2 MoreReceived 9 September 2020Revised 10 March 2021Accepted 25 2021DOI:https://doi.org/10.1103/PRXQuantum.2.020305Published American Physical Society under terms Creative Commons Attribution 4.0 International license. Further distribution work must maintain attribution to author(s) published article's title, journal citation, DOI.Published SocietyPhysics Subject Headings (PhySH)Research AreasOptical information processingQuantum communicationQuantum Information