A spinless spin qubit

TL;DR

This paper proposes a scalable, all-electrical spin qubit architecture using hole nanostructures with strong spin-orbit interactions, eliminating leakage states and improving robustness and compatibility with existing technologies.

Contribution

It introduces a novel spin qubit design leveraging hole nanostructures that removes leakage channels and reduces calibration needs, enhancing scalability and robustness.

Findings

Eliminates leakage states in spin qubits

Operates with two degenerate states, reducing calibration

Compatible with existing spin-1/2 qubit protocols

Abstract

All-electrical baseband control of qubits facilitates scaling up quantum processors by removing issues of crosstalk and heat generation. In semiconductor quantum dots, this is enabled by multi-spin qubit encodings, such as the exchange-only qubit, where high-fidelity readout and both single- and two-qubit operations have been demonstrated. However, their performance is limited by unavoidable leakage states that are energetically close to the computational subspace. In this work, we introduce an alternative, scalable spin qubit architecture that leverages strong spin-orbit interactions of hole nanostructures for baseband qubit operations while completely eliminating leakage channels and reducing the overall gate overhead. This encoding is intrinsically robust to local variability in hole spin properties and operates with two degenerate states, removing the need for precise calibration and mitigating heat generation from fast signal sources. Finally, our architecture is fully compatible with current technology, utilizing the same initialization, readout, and multi-qubit protocols of state-of-the-art spin-1/2 systems. By addressing critical scalability challenges, our design offers a robust and scalable pathway for semiconductor spin qubit technologies.