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Q: Fachverband Quantenoptik und Photonik

Q 47: Quantum Technologies – Sensing II

Q 47.4: Talk

Thursday, March 5, 2026, 11:45–12:00, P 5

Nanodiamond surface chemistry for improved quantum coherence in zero-field — •Tulika Agrawal for the AK Weil MPIP collaboration — Max Planck Institute for Polymer Research, Mainz, Germany

Nitrogen vacancy (NV) in diamond results in the application of diamond in quantum technologies such as sensing, computing and navigation. This is possible due to the sublevels of NV center which can be manipulated with microwave/RF and yet optically detectable. NV center has been proven to be a promising candidate due to their long coherence times (T2) at room temperature. However, the T2 times of NVs suffer drastic reduction when they are in nanodiamonds (NDs) instead of bulk diamond. Moreover, NDs are functionalized with a variety of chemical groups to make them compatible for desired application. This surface modification can cause a significant impact on T2 times of NV centers. Therefore, it has become crucial to investigate deeper into the relationship between surface chemistry and T2 times. In this work, T2 times have been investigated in two types of functionalized NDs, nanogel coated NDs (NDNG) and polyglycerol coated NDs (NDPG). To obtain T2 times in zero magnetic field, two different pulse sequences, Hahn-echo and geometric spin, have been employed. While the conventional EPR study has shown a reduction in surface spin noises upon functionalization, T2 measurements have distinctly shown the change in T2 times from NG to PG.

Keywords: Nanodiamond; NV center; Quantum sensing; Coherence time; Surface chemistry