Bonn 2025 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 14: Quantum Metrology and Sensing (joint session QI/Q)

Q 14.3: Talk

Monday, March 10, 2025, 17:45–18:00, HS VIII

Spin Quantum Magnetometry and Gradiometry: Towards clinical applications in unshielded environments — •Magnus Benke, Jixing Zhang, Michael Kübler, Yihua Wang, Anjana Karuvayalil, and Jörg Wrachtrup — 3rd Physics Institute, University of Stuttgart, Stuttgart

Highly sensitive magnetometers are an essential tool for material analysis and medical applications. The Nitrogen Vacancy (NV) centers in diamond provides a promising candidate for a quantum sensor offering high sensitivity together with an exceptional spatial resolution while operating at ambient conditions. Current comparable technology also only has a limited dynamic range which makes it susceptible to background magnetic noise outside of shielded environments. The NV sensor with its broad dynamic range does not suffer from this limitation and can be used to form a gradiometric sensor array of two or more magnetometers to cancel any background fields. This enables unshielded measurements of small magnetic fields orders of magnitude smaller than the surrounding environment.

In this work we present a DC-broadband magnetometer with improved sensitivity reaching a photon shot noise limit of sub-pT/√Hz using a CW-ODMR (Continuous-Wave Optically Detected Magnetic Resonance) measurement scheme. With two of these highly sensitive magnetometers, we build a gradiometer and achieved a reduction of an artificial background signal by 40 times without decreasing an applied test signal. These advancements open the door to magnetic field-related clinical applications in unshielded environments.

Keywords: Nitrogen vacancy center; Magnetometry; Gradiometry