Universal qubit control through FPGA-accelerated qubit classification, Hamiltonian estimation and real-time feedback [Part 2]

ORAL

Abstract

Gate-controlled spin qubits are a promising platform for implementing quantum processors [1,2] and now operate near the error-correctable threshold [3]. To correct errors, however, fast real-time feedback based on qubit measurements must be executed within the qubit coherence time. Moreover, continuous real-time feedback is also useful to tune and calibrate the qubit environment in order to maintain high fidelity gates and long coherence times.

Here, we use a singlet-triplet qubit implemented in a gallium arsenide double dot and FPGA-based single-shot readout classification on an OPX+ pulse processor (Quantum Machines [4]) to perform real-time Hamiltonian estimation [5]. The fluctuating Overhauser gradient within the double dot is estimated on-the-fly, based on single-shot classifications of separated singlet pairs, enabling coherent spin rotations of the electron pair. Together with exchange rotations, this method yields universal qubit control of a GaAs spin qubit without requiring a micromagnet or nuclear polarization protocols.



[1] A.M.J. Zwerver et al., Nat. Electron. 5, 184-190 (2022)

[2] S.G.J. Philips et al., Nature 609, 919-924 (2022)

[3] A. Noiri et al., Nature 601, 338–342 (2022)

[4] https://www.quantum-machines.co/opx+/

[5] M. Shulman et al., Nat. Comm., 5(1), 5156 (2014)

*This project was funded within the QuantERA II Programme that has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No 101017733.

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Presenters

  • Fabrizio Berritta

    • Niels Bohr Institute, University of Copenhagen

Authors

  • Fabrizio Berritta

    • Niels Bohr Institute, University of Copenhagen

  • Torbjørn R Rasmussen

    • Niels Bohr Institute, University of Copenhagen

  • Joost van der Heijden

    • Quantum Machines, QDevil

  • Federico Fedele

    • Niels Bohr Institute, University of Copenhagen
    • University of Oxford
    • University Of Oxford

  • Jan A Krzywda

    • Polish Academy of Sciences
    • Institute of Physics Polish Academy of Sciences

  • Saeed Fallahi

    • Purdue University, Microsoft Quantum Purdue
    • Physics and Astronomy, Purdue University
    • Purdue University

  • Geoff C Gardner

    • Purdue University
    • Materials Engineering, Purdue University
    • Department of Physics and Astronomy, Birck Nanotechnology Center, Purdue University

  • Michael J Manfra

    • Purdue University, Microsoft Quantum Purdue
    • Purdue University
    • Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA; Microsoft Quantum Lab, Purdue University, West Lafayette, IN, USA
    • Physics and Astronomy, Purdue University
    • Department of Physics and Astronomy, Birck Nanotechnology Center, School of Electrical and Computer Engineering and Microsoft Quantum Lab West Lafayette, Purdue University
    • Department of Physics and Astronomy and Nanotechnology Center Purdue University, Microsoft Quantum Lab West Lafayette
    • Department of Physics and Astronomy, Birck Nanotechnology Center, School of Materials Engineering and School of Electrical and Computer Engineering, Purdue University

  • Evert Van Nieuwenburg

    • Niels Bohr Institute, University of Copenhagen

  • Jeroen Danon

    • Norwegian Univ Tech (NTNU)
    • Norwegian University of Science and Technology

  • Anasua Chatterjee

    • Niels Bohr Institute, University of Copenhagen
    • Univ of Copenhagen

  • Ferdinand Kuemmeth

    • Niels Bohr Institute, University of Copenhagen
    • Niels Bohr Institute, University of Copenhagen. Quantum Machines, QDevil
    • Niels Bohr Inst