Quantum-grade nanodiamonds for sensing applications

Nanodiamonds (NDs) with nitrogen-vacancy (NV) centers have gained attention as nanoscale quantum sensors, offering unique capabilities for detecting magnetic fields, temperature changes, and redox processes. These sensing functions rely on the sensitivity of the NV electron spin to its local surroundings, which can be read out optically with high spatial and temporal resolution. Realizing the full potential of NV-NDs in diverse applications requires careful surface engineering to preserve spin properties, enhance colloidal stability, and enable sensing selectivity. Despite considerable progress in the ND field [1], the widespread real-world adoption of these materials has been hindered by the absence of scalable and cost-effective methods for producing luminescent NDs.

In this talk, I will discuss recent advances in the development of ND-based probes, including surface modifications and the design of tailored chemical transducers that translate probed quantities into an NV-detectable signal. Further, I will introduce a novel single-step method for the scalable production of NV centers in 50-nm NDs. Traditional approaches rely on costly and time-consuming multi-step irradiation and annealing processes [2]. Our approach employs high-temperature plastic deformation of HPHT NDs in a cubic press and achieves NV centers with superior charge stability, T1 relaxation times approaching 1 ms, and significantly enhanced optical Rabi contrast. This process also enables the formation of H3 centers, previously inaccessible in NDs of this size. Altogether, this process represents a significant step toward industrial-scale production of quantum-grade luminescent NDs for quantum technologies.

References:
[1] Zhang T. et al., ACS Sensors, 2021 6 (6), 2077-2107
[2] Gulka M. et al., Carbon, 2024 224, 119062