In conventional exchange-only (EO) spin qubit demonstrations, quantum gates have been implemented using sequences of individually pulsed pairwise exchange interactions with only one exchange coupling active at a time. Alternatively, multiple non-commuting exchange interactions can be pulsed simultaneously, reducing circuit depths and providing protection against leakage. We demonstrate high-fidelity quantum control of an always-on exchange-only (AEON) qubit, operated using simultaneous exchange pulses in a triangular quantum dot (QD) array. We use blind randomized benchmarking to characterize the performance of the full AEON single-qubit Clifford gate set, achieving an average Clifford gate fidelity FC1 = 99.86%. Extensions of this work may enable more efficient EO two-qubit entangling gates as well as the implementation of native i-Toffoli gates in Loss-DiVincenzo single-spin qubits.
@article{arxiv.2508.01033,
title = {Demonstration of an always-on exchange-only spin qubit},
author = {Joseph D. Broz and Jesse C. Hoke and Edwin Acuna and Jason R. Petta},
journal= {arXiv preprint arXiv:2508.01033},
year = {2025}
}