Detecting Topological Invariants in Nonunitary Discrete-Time Quantum Walks

Xiang Zhan, Lei Xiao, Zhihao Bian, Kunkun Wang, Xingze Qiu, Barry C. Sanders, Wei Yi, and Peng Xue
Phys. Rev. Lett. 119, 130501 – Published 27 September 2017
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Abstract

We report the experimental detection of bulk topological invariants in nonunitary discrete-time quantum walks with single photons. The nonunitarity of the quantum dynamics is enforced by periodically performing partial measurements on the polarization of the walker photon, which effectively introduces loss to the dynamics. The topological invariant of the nonunitary quantum walk is manifested in the quantized average displacement of the walker, which is probed by monitoring the photon loss. We confirm the topological properties of the system by observing localized edge states at the boundary of regions with different topological invariants. We further demonstrate the robustness of both the topological properties and the measurement scheme of the topological invariants against disorder.

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  • Received 28 June 2017

DOI:https://doi.org/10.1103/PhysRevLett.119.130501

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & Technology

Authors & Affiliations

Xiang Zhan1, Lei Xiao1, Zhihao Bian1, Kunkun Wang1, Xingze Qiu2,3, Barry C. Sanders3,4,5,6, Wei Yi2,3,*, and Peng Xue1,7,†

  • 1Department of Physics, Southeast University, Nanjing 211189, China
  • 2Key Laboratory of Quantum Information, University of Science and Technology of China, CAS, Hefei 230026, China
  • 3Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, CAS, Hefei 230026, China
  • 4Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, CAS, Hefei 230026, China
  • 5Institute for Quantum Science and Technology, University of Calgary, Alberta T2N 1N4, Canada
  • 6Program in Quantum Information Science, Canadian Institute for Advanced Research, Toronto, Ontario M5G 1M1, Canada
  • 7State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China

  • *wyiz@ustc.edu.cn
  • gnep.eux@gmail.com

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Issue

Vol. 119, Iss. 13 — 29 September 2017

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