Enhancement of quantum coherence in solid-state qubits via interface engineering.

Lo, Wing Ki; Zhang, Yaowen; Chow, Ho Yin; Wu, Jiahao; Leung, Man Yin; Ho, Kin On; Du, Xuliang; Chen, Yifan et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

Shallow nitrogen-vacancy (NV) centers in diamond are promising quantum sensors but suffer from noise-induced short coherence times due to bulk and surface impurities. We present interfacial engineering via oxygen termination and graphene patching, extending shallow NV coherence to over 1 ms, approaching the T<sub>1</sub> limit. Raman spectroscopy and density-functional theory reveal surface termination-driven graphene charge transfer reduces spin noise by pairing surface electrons, supported by double electron-electron resonance spectroscopy showing fewer unpaired spins. Enhanced sensitivity enables detection of single weakly coupled <sup>13</sup>C nuclear spins and external <sup>11</sup>B spins from a hexagonal boron nitride (h-BN) layer, achieving nanoscale nuclear magnetic resonance. A protective h-BN top layer stabilizes the platform, ensuring robustness against harsh treatments and compatibility with target materials. This integrated approach advances practical quantum sensing by combining extended coherence, improved sensitivity, and device durability.