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Efficient Experimental Verification of Quantum Gates with Local Operations

Rui-Qi Zhang, Zhibo Hou, Jun-Feng Tang, Jiangwei Shang, Huangjun Zhu, Guo-Yong Xiang, Chuan-Feng Li, and Guang-Can Guo
Phys. Rev. Lett. 128, 020502 – Published 14 January 2022
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Abstract

Verifying the correct functioning of quantum gates is a crucial step toward reliable quantum information processing, but it becomes an overwhelming challenge as the system size grows due to the dimensionality curse. Recent theoretical breakthroughs show that it is possible to verify various important quantum gates with the optimal sample complexity of O(1/ε) using local operations only, where ε is the estimation precision. In this Letter, we propose a variant of quantum gate verification (QGV) that is robust to practical gate imperfections and experimentally realize efficient QGV on a 2-qubit controlled-not gate and a 3-qubit Toffoli gate using only local state preparations and measurements. The experimental results show that, by using only 1600 and 2600 measurements on average, we can verify with 95% confidence level that the implemented controlled-not gate and Toffoli gate have fidelities of at least 99% and 97%, respectively. Demonstrating the superior low sample complexity and experimental feasibility of QGV, our work promises a solution to the dimensionality curse in verifying large quantum devices in the quantum era.

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  • Received 27 June 2021
  • Accepted 24 November 2021

DOI:https://doi.org/10.1103/PhysRevLett.128.020502

© 2022 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & Technology

Authors & Affiliations

Rui-Qi Zhang1,2,*, Zhibo Hou1,2,*, Jun-Feng Tang1,2, Jiangwei Shang3,†, Huangjun Zhu4,5,6,‡, Guo-Yong Xiang1,2,§, Chuan-Feng Li1,2, and Guang-Can Guo1,2

  • 1CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, People’s Republic of China
  • 2CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, People’s Republic of China
  • 3Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement of Ministry of Education, School of Physics, Beijing Institute of Technology, Beijing 100081, China
  • 4State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
  • 5Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
  • 6Center for Field Theory and Particle Physics, Fudan University, Shanghai 200433, China

  • *R.-Q. Z. and Z. H. contributed equally to this work.
  • jiangwei.shang@bit.edu.cn
  • zhuhuangjun@fudan.edu.cn
  • §gyxiang@ustc.edu.cn

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Issue

Vol. 128, Iss. 2 — 14 January 2022

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