Design of always-on exchange devices for SAGE qubits

ORAL

Abstract

We propose a design for the implementation of singlet-only always-on gapless exchange (SAGE) qubits [1], in which the exchange interaction between 4 quantum dots is always on. Very precise control over pair-wise exchange between dots is required to perform high-fidelity gates on SAGE qubits. A 10MHz always-on exchange and a 10-100 MHz controlled exchange variation over a 100mV span is desired. To aid in the design of this complex multi-dot device with these constraints, we perform fully self-consistent multiparticle Schrodinger-Poisson device simulations incorporating realistic gate geometries. Due to large cross-talk and high tunnel-coupling between the dots, we find that precise virtualization of the gates is required to operate in the desired regime. With this virtualization, we find designs that operate within the constraints and greatly enhance the probability of first-pass success in fabrication.

[1] Foulk, N. L., Hoffman, S., Laubscher, K., & Das Sarma, S. (2025). Singlet-Only Always-On Gapless Exchange Qubits with Baseband Control. Physical Review Letters, 135(10), 106202.

*The authors acknowledge support from Modeling center: ARO W911NF-25-1-0141.

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Presenters

  • Ayan Kumar

    • University of California, Los Angeles

Authors

  • Ayan Kumar

    • University of California, Los Angeles

  • Mark F Gyure

    • University of California, Los Angeles
    • UCLA

  • Chris R Anderson

    • University of California, Los Angeles (UCLA)
    • University of California, Los Angeles

  • David Wyman Kanaar

    • UCLA
    • University of California, Los Angeles
    • University of Maryland Baltimore County

  • Adam R Mills

    • Laboratory for Physical Sciences (LPS)

  • Silas Hoffman

    • Laboratory for Physical Sciences (LPS)

  • Samuel George Carter

    • Laboratory for Physical Sciences (LPS)