We show that Heisenberg exchange interactions between the neighboring spins comprising an ensemble spin qubit (E-qubit) can act as an intrinsic error mitigator, increasing gate fidelity even at high temperatures. As an example, the fidelity of a {\pi} gate applied to E-qubits above 1 K was studied by tuning the ferromagnetic exchange strength to show an exchange coupled E-qubit exhibits higher fidelity than a single-spin based qubit. We also investigate the coherence properties of E-qubits and find that the coherence time of an E-qubit extends linearly with the number of spins in the ensemble. This suggests that exchange interactions effectively suppress decoherence induced by thermal noise, achieving a coherence time greater than 1 ms at 1 K with an ensemble of only seven spins. Additionally, the ferromagnetic isotropic exchange prevents fidelity loss induced by spatial field gradients/inhomogeneity in Zeeman and/or control fields. Therefore, exchange-coupled spin qubits could enable fault-tolerant quantum operations and long-coherence times at elevated temperatures (>1 K).
@article{arxiv.2503.12071,
title = {Exchange-Coupled Spins for Robust High-Temperature Qubits},
author = {Aniruddha Chakraborty and Md. Fahim F. Chowdhury and Mohamad Niknam and Louis S. Bouchard and Jayasimha Atulasimha},
journal= {arXiv preprint arXiv:2503.12071},
year = {2025}
}