Diamond is a promising platform for quantum information processing as it can host highly coherent qubits that could allow for the construction of large quantum registers. A prerequisite for such devices is a coherent interaction between nitrogen vacancy (NV) electron spins. Entanglement between dipolar-coupled NV spin pairs has been demonstrated, but with a limited entanglement fidelity and its error sources have not been characterized. Here, we design and implement a robust, easy to implement entangling gate between NV spins in diamond and quantify the influence of multiple error sources on the gate performance. Experimentally, we demonstrate a record gate fidelity of F=(96.0±2.5) % under ambient conditions. Our identification of the dominant errors paves the way towards NV-NV gates beyond the error correction threshold.
@article{arxiv.2406.04199,
title = {High-Fidelity Electron Spin Gates for Scaling Diamond Quantum Register},
author = {Timo Joas and Florian Ferlemann and Roberto Sailer and Philipp J. Vetter and Jingfu Zhang and Ressa S. Said and Tokuyuki Teraji and Shinobu Onoda and Tommaso Calarco and Genko Genov and Matthias M. Müller and Fedor Jelezko},
journal= {arXiv preprint arXiv:2406.04199},
year = {2025}
}