Broadband sensing with hybrid-spin decoupling using nitrogen-vacancy centres

The nitrogen-vacancy (NV) center is one of various defects in diamond, consisting of a substitutional nitrogen and a neighboring missing carbon atom. It is a promising candidate for various applications given its high sensitivities under ambient conditions. With its electron spin, it can sense quantities such as magnetic fields, important for battery monitoring, and temperature, useful in biology for mapping of the cell activity. Moreover, quantum sensors are gaining attention for fundamental physics [1,2].

High sensitivities are thus essential for quantum sensors, with noise sources a significant limiting factor. Decoupling sequences increase coherence times and hence sensitivities, but only signals with a frequency in a narrow range are detected. Comagnetometers utilizing gaseous spin mixtures work within the self-compensating regime to offer an alternative way to reduce the effect of low-frequency noise [3].

We aim to design a protocol for solid-state spins that filters magnetic noise, but retains sensitivity to certain broadband signals. Combining the nitrogen nuclear spin and the electron spin of NV centers, we propose a hybrid-spin decoupling method which is resilient to magnetic noise, while it can measure fields that have a different effect on each spin [4]. The solid state nature of diamond, where each nuclear-spin-electron-spin comes as a pair, offers a unique method compared to current comagnetometers. Advantages include a large bandwidth of filtered noise, the option to lower the temperature to increase the sensitivity further, and a high spatial resolution. This method is useful for gradient detection, quantum memory, gyroscopes, and for novel-particle searches.

[1] JHEP 2025, 83 (2025).

[2] PRD 111, 075028 (2025).

[3] PRL 89, 253002 (2002).

[4] arXiv:2511.16732 (2025).