Entanglement-free certification of entangling gates

M. P. Almeida, Mile Gu, Alessandro Fedrizzi, Matthew A. Broome, Timothy C. Ralph, and Andrew G. White
Phys. Rev. A 89, 042323 – Published 23 April 2014

Abstract

Not all quantum protocols require entanglement to outperform their classical alternatives. The nonclassical correlations that lead to a quantum advantage are conjectured to be captured by quantum discord. Here we demonstrate that discord has an immediate practical application: it allows a client who lacks the ability to generate entanglement or conduct quantum measurements to certify whether an untrusted party has entangling gates. We implement our protocol in the discrete-variable regime with photonic qubits and show its success in the presence of high levels of noise and imperfect gate operations. Our technique offers a practical method to test claims of quantum processing and to benchmark entangling operations for physical architectures in which only highly mixed states are available.

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  • Received 14 January 2013
  • Revised 1 July 2013

DOI:https://doi.org/10.1103/PhysRevA.89.042323

©2014 American Physical Society

Authors & Affiliations

M. P. Almeida1,2,*, Mile Gu3,4, Alessandro Fedrizzi1,2, Matthew A. Broome1,2, Timothy C. Ralph2, and Andrew G. White1,2

  • 1Centre for Engineered Quantum Systems, School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
  • 2Centre for Quantum Computer and Communication Technology, School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
  • 3Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
  • 4Centre for Quantum Technologies, National University of Singapore, Singapore

  • *marcelo@physics.uq.edu.au

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Vol. 89, Iss. 4 — April 2014

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