Anatoly Kulikov

Complete Self-Testing of a System of Remote Superconducting Qubits

  1. Simon Storz,
  2. Anatoly Kulikov,
  3. Josua D. Schär,
  4. Victor Barizien,
  5. Xavier Valcarce,
  6. Florence Berterottière,
  7. Nicolas Sangouard,
  8. Jean-Daniel Bancal,
  9. and Andreas Wallraff
Self-testing protocols enable the certification of quantum systems in a device-independent manner, i.e. without knowledge of the inner workings of the quantum devices under test. Here,
we demonstrate this high standard for characterization routines with superconducting circuits, a prime platform for building large-scale quantum computing systems. We first develop the missing theory allowing for the self-testing of Pauli measurements. We then self-test Bell pair generation and measurements at the same time, performing a complete self-test in a system composed of two entangled superconducting circuits operated at a separation of 30 meters. In an experiment based on 17 million trials, we measure an average CHSH (Clauser-Horne-Shimony-Holt) S-value of 2.236. Without relying on additional assumptions on the experimental setup, we certify an average Bell state fidelity of at least 58.9% and an average measurement fidelity of at least 89.5% in a device-independent manner, both with 99% confidence. This enables applications in the field of distributed quantum computing and communication with superconducting circuits, such as delegated quantum computing.
arxiv pdf

Realization of a quantum random generator certified with the Kochen-Specker theorem

  1. Anatoly Kulikov,
  2. Markus Jerger,
  3. Anton Potočnik,
  4. Andreas Wallraff,
  5. and Arkady Fedorov
Random numbers are required for a variety of applications from secure communications to Monte-Carlo simulation. Yet randomness is an asymptotic property and no output string generated
by a physical device can be strictly proven to be random. We report an experimental realization of a quantum random number generator (QRNG) with randomness certified by quantum contextuality and the Kochen-Specker theorem. The certification is not performed in a device-independent way but through a rigorous theoretical proof of each outcome being value-indefinite even in the presence of experimental imperfections. The analysis of the generated data confirms the incomputable nature of our QRNG.
arxiv pdf