Coincidence postselection for genuine multipartite nonlocality: Causal diagrams and threshold efficiencies
Year: 2022
Authors: Gebhart V., Smerzi A.
Autors Affiliation: QSTAR, INO CNR & LENS, Largo Enr Fermi 2, I-50125 Florence, Italy.
Abstract: Genuine multipartite nonlocality (GMN), the strongest form of multipartite nonlocality that describes fully collective nonlocal correlations among all experimental parties, can be observed when different distant parties each locally measure a particle from a shared entangled many-particle state. For the demonstration of GMN, the experimentally observed statistics are typically postselected: Events for which some parties do not detect a particle must be discarded. This coincidence postselection generally leads to the detection loophole that invalidates a proper nonlocality demonstration. In this work, we address how to close the detection loophole for a coincidence detection in demonstrations of nonlocality and GMN. We first show that if the number of detected particles is conserved, i.e., using ideal and noiseless experimental devices, one can employ causal diagrams and the no-signaling principle to prove that a coincidence postselection cannot create any detection loophole. Furthermore, for realistic experimental devices with finite detection efficiencies, we show how a general Bell inequality can be sharpened such that its new version is still valid after a postselection of the measurement data. In this case, there are threshold detection efficiencies that, if surpassed in the experiment, lead to the possibility of demonstrating nonlocality and GMN without opening the detection loophole. Our results imply that genuine N-partite nonlocality can be generated from N independent particle sources even when allowing for nonideal detectors.
Journal/Review: PHYSICAL REVIEW A
Volume: 106 (6) Pages from: 62202-1 to: 62202-12
More Information: This work was supported by the European Commission through the H2020 QuantERA ERA-NET Cofund in Quantum Technologies project MENTA.KeyWords: Bells-inequality; Proposed Experiment; Nonseparability; ViolationDOI: 10.1103/PhysRevA.106.062202ImpactFactor: 2.900Citations: 1data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2024-11-03References taken from IsiWeb of Knowledge: (subscribers only)Connecting to view paper tab on IsiWeb: Click hereConnecting to view citations from IsiWeb: Click here
