Combining the long-coherence of spin qubits and the capability to transmit information and entanglement through photons, spin-photon interfaces (SPIs) are a promising platform for networked quantum computation and long-distance quantum communication. SPIs that possess local `memory' qubits in addition to the optically coupled `communication' qubit can improve remote entanglement fidelities through brokered entanglement schemes and entanglement purification. In these schemes, it is critical to protect the memory qubit from decoherence during entanglement operations on the communications qubit. Silicon, a platform with mature microelectronic and nanophotonic fabrication, is host to the T centre, an SPI with emission in the telecommunications O-band that directly integrates with silicon nanophotonics. Cavity-coupled T centres are a platform for brokered entanglement distribution in silicon photonic circuits and over long-distance optical fibre links. The T centre's electron and nuclear spin qubits are an intrinsic register of communication and memory qubits respectively, with anisotropic hyperfine coupling. In this work we determine the T centre's hydrogen hyperfine coupling tensor. We also introduce schemes to protect against dephasing or eliminate relaxation of the T centre's hydrogen memory qubit during optical excitation. These results address a key challenge for practical T centre quantum networks.
Cite
@article{arxiv.2512.16047,
title = {Silicon T centre hyperfine structure and memory protection schemes},
author = {Nicholas Brunelle and Joshua Kanaganayagam and Mehdi Keshavarz and Chloe Clear and Oney Soykal and Myles Ruether and Adam DeAbreu and Amirhossein AlizadehKhaledi and Yihuang Xiong and Nikolay V. Abrosimov and Geoffroy Hautier and Michael Thewalt and Stephanie Simmons and Daniel Higginbottom},
journal= {arXiv preprint arXiv:2512.16047},
year = {2026}
}