Entanglement is central to quantum science and technology. Atomic defects in two-dimensional (2D) van der Waals (vdW) materials offer exciting prospects for quantum sensing, with spatial resolution reaching 1 nm demonstrated using scanning probe techniques. However, entangling qubits in vdW materials remains elusive. Here we report room-temperature quantum entanglement between an optically addressable electron spin and a strongly coupled 13C nuclear spin in hexagonal boron nitride (hBN). We extend the electron spin coherence to 38 μs with dynamical decoupling, and create maximally entangled Bell states with a fidelity up to 0.89. We further use the nuclear spin as a long-lived quantum memory to enhance AC magnetic field sensing via correlation spectroscopy. These results establish entangled spin qubits in hBN as a robust platform for advanced quantum technologies based on 2D materials.
@article{arxiv.2509.23170,
title = {Room-temperature quantum entanglement in a van der Waals material},
author = {Xingyu Gao and Zhun Ge and Saakshi Dikshit and Sumukh Vaidya and Peng Ju and Tongcang Li},
journal= {arXiv preprint arXiv:2509.23170},
year = {2025}
}