Si/SiO<sub>2</sub> Roughness: Variability, tunability and crosstalk in CMOS spin qubits

ORAL

Abstract

Fault tolerant quantum computation will require building processors with millions of qubits. The CMOS spin qubit technology - fabricated with the same materials and techniques as transistors - promises a highly scalable pathway to achieve these numbers. Initial experiments in two-qubit devices have demonstrated high gate fidelities and long coherence times. However, CMOS qubits are defined by the spin state of single electrons accumulated at the Si/SiO2 interface, making them susceptible to potential sources of disorder in the oxide. Even though modern fabrication processes lead to reliable and stable oxides, their growth leads to an atomically rough interface. In this talk, we will explore the impact of this roughness on the most important qubit parameters. By comparing atomistic simulations in random realistic surfaces with measurements of up to 10 qubits in 5 identical devices, we obtained a reliable estimate of the variability of our qubits. Each of these qubit parameters has some range of electrical tunability from nearby gates that enables local controllability. We show that the sign and the magnitude of the Stark shift from each gate depends on the local surface profile too. This is a source of crosstalk as gate detunings can cause lateral displacements in the quantum dots nearby. We will analyze the possible effects of this crosstalk in a scalable qubit architecture. Based on these statistics, realistic protocols for scaling CMOS spin qubits may be developed.

*We acknowledge support from the Australian Research Council (DE190101397, FL190100167 and CE170100012) the US Army Research Office (W911NF-17-1-0198), Sydney Quantum Academy and the NSW Node of the Australian National Fabrication Facility. This project was undertaken with the assistance of resources and services from the National Computational Infrastructure (NCI), which is supported by the Australian Government and includes computations using the computational cluster Katana supported by ResearchTechnology Services at UNSW Sydney. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Office or the U.S. Government.

–

Publication: Manuscript in preparation

Presenters

  • Jesus D Cifuentes Pardo

    • University of New South Wales
    • 1) University of New South Wales

Authors

  • Jesus D Cifuentes Pardo

    • University of New South Wales
    • 1) University of New South Wales

  • Tuomo I Tanttu

    • 1) University of New South Wales, 2) Diraq Pty. Ltd
    • 1) University of New South Wales 2) Diraq
    • 1) University of New South Wales, 2) Diraq Pty. Ltd.

  • Yue Y Huang

    • UNSW
    • 1) University of New South Wales
    • University of New South Wales

  • William Gilbert

    • 1) University of New South Wales, 2) Diraq Pty. Ltd
    • 1) University of New South Wales, 2) Diraq Pty. Ltd.

  • Ensar Vahapoglu

    • 1) University of New South Wales, 2) Diraq Pty. Ltd.
    • 1) University of New South Wales

  • Santiago Serrano

    • 1) University of New South Wales, 2) Diraq Pty. Ltd.
    • University of New South Wales

  • MengKe Feng

    • University of New South Wales
    • 1) University of New South Wales

  • Arne Laucht

    • 1) University of New South Wales, 2) Diraq Pty. Ltd
    • 1) University of New South Wales, 2) Diraq Pty. Ltd.
    • University of New South Wales
    • University of New South Wales, Diraq Pty. Ltd.

  • Henry Yang

    • 1) University of New South Wales, 2) Diraq Pty. Ltd
    • 1) University of New South Wales, 2) Diraq Pty. Ltd.
    • UNSW Sydney

  • Christopher Escott

    • 1) University of New South Wales, 2) Diraq Pty. Ltd
    • 1) University of New South Wales, 2) Diraq Pty. Ltd.

  • Rajib Rahman

    • University of New South Wales
    • 1) University of New South Wales

  • Fay E Hudson

    • 1) University of New South Wales, 2) Diraq Pty. Ltd
    • 1) University of New South Wales, 2) Diraq Pty. Ltd.
    • University of New South Wales

  • Wee Han Lim

    • 1) University of New South Wales, 2) Diraq Pty. Ltd
    • 1) University of New South Wales, 2) Diraq Pty. Ltd.
    • University of New South Wales

  • Andre Saraiva

    • 1) University of New South Wales, 2) Diraq Pty. Ltd
    • 1) University of New South Wales, 2) Diraq Pty. Ltd.
    • UNSW Sydney
    • UNSW
    • Diraq
    • University of New South Wales, Diraq Pty. Ltd.

  • Andrew S Dzurak

    • 1) University of New South Wales, 2) Diraq Pty. Ltd
    • 1) University of New South Wales, 2) Diraq Pty. Ltd.
    • University of New South Wales
    • University of New South Wales, Diraq Pty. Ltd.