Experimentally superposing two pure states with partial prior knowledge

Keren Li, Guofei Long, Hemant Katiyar, Tao Xin, Guanru Feng, Dawei Lu, and Raymond Laflamme
Phys. Rev. A 95, 022334 – Published 23 February 2017

Abstract

Superposition, arguably the most fundamental property of quantum mechanics, lies at the heart of quantum information science. However, how to create the superposition of any two unknown pure states remains as a daunting challenge. Recently, it was proved that such a quantum protocol does not exist if the two input states are completely unknown, whereas a probabilistic protocol is still available with some prior knowledge about the input states [M. Oszmaniec et al., Phys. Rev. Lett. 116, 110403 (2016)]. The knowledge is that both of the two input states have nonzero overlaps with some given referential state. In this work, we experimentally realize the probabilistic protocol of superposing two pure states in a three-qubit nuclear magnetic resonance system. We demonstrate the feasibility of the protocol by preparing a families of input states, and the average fidelity between the prepared state and expected superposition state is over 99%. Moreover, we experimentally illustrate the limitation of the protocol that it is likely to fail or yields very low fidelity, if the nonzero overlaps are approaching zero. Our experimental implementation can be extended to more complex situations and other quantum systems.

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  • Received 10 September 2016

DOI:https://doi.org/10.1103/PhysRevA.95.022334

©2017 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & TechnologyGeneral Physics

Authors & Affiliations

Keren Li1,2, Guofei Long2, Hemant Katiyar2, Tao Xin1, Guanru Feng2, Dawei Lu2,*, and Raymond Laflamme2,3,4

  • 1State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
  • 2Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo N2L 3G1, Ontario, Canada
  • 3Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada
  • 4Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada

  • *Corresponding author: d29lu@uwaterloo.ca

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Issue

Vol. 95, Iss. 2 — February 2017

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