Measurements of Nonlocal Variables and Demonstration of the Failure of the Product Rule for a Pre- and Postselected Pair of Photons

Xiao-Ye Xu, Wei-Wei Pan, Qin-Qin Wang, Jan Dziewior, Lukas Knips, Yaron Kedem, Kai Sun, Jin-Shi Xu, Yong-Jian Han, Chuan-Feng Li, Guang-Can Guo, and Lev Vaidman
Phys. Rev. Lett. 122, 100405 – Published 15 March 2019

Abstract

We report the first implementation of the von Neumann instantaneous measurements of nonlocal variables, which becomes possible due to technological achievements in creating hyperentangled photons. Tests of reliability and of the nondemolition property of the measurements have been performed with high precision, showing the suitability of the scheme as a basic ingredient of numerous quantum information protocols. The method allows us to demonstrate for the first time with strong measurements a special feature of pre- and postselected quantum systems: the failure of the product rule. It has been verified experimentally that for a particular pre- and postselected pair of particles, a single measurement on particle A yields with certainty σxA=1, a single measurement on particle B yields with certainty σyB=1, and a single nonlocal measurement on particles A and B yields with certainty σxAσyB=1.

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  • Received 14 May 2018
  • Revised 26 January 2019

DOI:https://doi.org/10.1103/PhysRevLett.122.100405

© 2019 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & TechnologyGeneral Physics

Authors & Affiliations

Xiao-Ye Xu1,2, Wei-Wei Pan1,2, Qin-Qin Wang1,2, Jan Dziewior3,4, Lukas Knips3,4, Yaron Kedem5, Kai Sun1,2, Jin-Shi Xu1,2, Yong-Jian Han1,2, Chuan-Feng Li1,2,*, Guang-Can Guo1,2, and Lev Vaidman6,†

  • 1CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
  • 2Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
  • 3Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
  • 4Department für Physik, Ludwig-Maximilians-Universität, 80797 München, Germany
  • 5Department of Physics, Stockholm University, AlbaNova University Center, 106 91 Stockholm, Sweden
  • 6Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel

  • *cfli@ustc.edu.cn
  • vaidman@post.tau.ac.il

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Vol. 122, Iss. 10 — 15 March 2019

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