Physics-informed tracking of qubit fluctuations

Physical Review Applied, vol. 22

Abstract

Environmental fluctuations degrade the performance of solid-state qubits but can in principle be mitigated by real-time Hamiltonian estimation down to timescales set by the estimation efficiency. We implement a physics-informed and an adaptive Bayesian estimation strategy and apply them in real time to a semiconductor spin qubit. The physics-informed strategy propagates a probability distribution inside the quantum controller according to the Fokker-Planck equation, appropriate for describing the effects of nuclear spin diffusion in gallium arsenide. Evaluating and narrowing the anticipated distribution by a predetermined qubit probe sequence enables improved dynamical tracking of the uncontrolled magnetic field gradient within the singlet-triplet qubit. The adaptive strategy replaces the probe sequence by a small number of qubit probe cycles, with each probe time conditioned on the previous measurement outcomes, thereby further increasing the estimation efficiency. The combined real-time estimation strategy efficiently tracks low-frequency nuclear spin fluctuations in solid-state qubits, and can be applied to other qubit platforms by tailoring the appropriate update equation to capture their distinct noise sources. Published by the American Physical Society 2024

Authors 11

1. Fabrizio Berritta
   Affiliation as printed

   Niels Bohr Institute

2. Jan A. Krzywda Aachen

   Leiden University

   Affiliation as printed

   Leiden University

3. Jacob Benestad

   Norwegian University of Science and Technology

   Affiliation as printed

   Norwegian University of Science and Technology

4. Joost van der Heijden
   Affiliation as printed

   QDevil, Quantum Machines

5. Federico Fedele

   University of Oxford

   Affiliation as printed

   Niels Bohr Institute

   University of Oxford

6. G. C. Gardner

   Purdue University West Lafayette

   Affiliation as printed

   Purdue University, West Lafayette

7. Michael J. Manfra

   Purdue University West Lafayette

   Affiliation as printed

   Purdue University, West Lafayette

8. Evert van Nieuwenburg Aachen

   Leiden University

   Affiliation as printed

   Leiden University

9. Jeroen Danon

   Norwegian University of Science and Technology

   Affiliation as printed

   Norwegian University of Science and Technology

10. Anasua Chatterjee
    Affiliation as printed

    Niels Bohr Institute

11. Ferdinand Kuemmeth
    Affiliation as printed

    Niels Bohr Institute

    QDevil, Quantum Machines