Self-Testing of a Single Quantum Device Under Computational Assumptions

Authors Tony Metger , Thomas Vidick

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Author Details

Tony Metger
  • Institute for Theoretical Physics, ETH Zürich, Switzerland
Thomas Vidick
  • Department of Computing and Mathematical Sciences, California Institute of Technology, Pasadena, CA, USA


We thank Andrea Coladangelo, Andru Gheorghiu, Anand Natarajan, and Tina Zhang for helpful discussions; Andrea Coladangelo, Andru Gheorghiu, Urmila Mahadev, and Akihiro Mizutani for comments on the manuscript; and Lídia del Rio for pointing out the reference [Bharti et al., 2019]. This work was carried out while Tony Metger was a visiting student researcher at the Department of Computing and Mathematical Sciences at Caltech.

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Tony Metger and Thomas Vidick. Self-Testing of a Single Quantum Device Under Computational Assumptions. In 12th Innovations in Theoretical Computer Science Conference (ITCS 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 185, pp. 19:1-19:12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


Self-testing is a method to characterise an arbitrary quantum system based only on its classical input-output correlations, and plays an important role in device-independent quantum information processing as well as quantum complexity theory. Prior works on self-testing require the assumption that the system’s state is shared among multiple parties that only perform local measurements and cannot communicate. Here, we replace the setting of multiple non-communicating parties, which is difficult to enforce in practice, by a single computationally bounded party. Specifically, we construct a protocol that allows a classical verifier to robustly certify that a single computationally bounded quantum device must have prepared a Bell pair and performed single-qubit measurements on it, up to a change of basis applied to both the device’s state and measurements. This means that under computational assumptions, the verifier is able to certify the presence of entanglement, a property usually closely associated with two separated subsystems, inside a single quantum device. To achieve this, we build on techniques first introduced by Brakerski et al. (2018) and Mahadev (2018) which allow a classical verifier to constrain the actions of a quantum device assuming the device does not break post-quantum cryptography.

Subject Classification

ACM Subject Classification
  • Theory of computation → Quantum computation theory
  • Quantum computing
  • quantum cryptography
  • device-independence
  • self-testing
  • post-quantum cryptography


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