Quantum networks might enable quantum communication and distributed quantum computation. Solid-state defects are promising platforms for such networks, because they provide an optical interface for remote entanglement distribution and a nuclear-spin register to store and process quantum information. A key challenge towards larger networks is to improve the storage of previously generated entangled states during new entanglement generation. Here, we introduce a method that uses `spectator' qubits combined with real-time decision making and feedforward to mitigate dephasing of stored quantum states during remote entanglement sequences. We implement the protocol using a single NV center in diamond and demonstrate improved memory fidelity. Our results show that spectator qubits can improve quantum network memory using minimal overhead and naturally present resources, making them a promising addition for near-term testbeds for quantum networks.
@article{arxiv.2505.05582,
title = {Quantum-network nodes with real-time noise mitigation using spectator qubits},
author = {S. J. H. Loenen and Y. Wang and N. Demetriou and C. E. Bradley and T. H. Taminiau},
journal= {arXiv preprint arXiv:2505.05582},
year = {2026}
}
Comments
Main text + main figures + references = 9 pages. Supplementary information + supplementary information figures = 17 pages