Exchange-Coupled Spins for Robust High-Temperature Qubits

• URL: http://arxiv.org/abs/2503.12071v1
• Date: Sat, 15 Mar 2025 10:14:56 GMT
• Title: Exchange-Coupled Spins for Robust High-Temperature Qubits
• Authors: Aniruddha Chakraborty, Md. Fahim F. Chowdhury, Mohamad Niknam, Louis S. Bouchard, Jayasimha Atulasimha,
• Abstract summary: 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.<n>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.
• Score: 0.059918512541940964
• License: http://creativecommons.org/licenses/by-nc-sa/4.0/
• Abstract: 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).

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