Group seminar at LMU and Zoom: Diamond Quantum Magnetometry: from Simulating NV Centre Dynamics to Visualizing Supercurrent Flow

Yichen Cai,University of Cambridge, UK
Group seminar at LMU seminar room and Zoom
Tuesday, 23 September, 10:00am (MEZ)

Diamond quantum magnetometry (DQM) leverages spin properties of nitrogen vacancy (NV) centres in diamond to detect stray magnetic fields with high sensitivity and spatial resolution. Over the past decade, various spin control techniques have been developed to increase the sensitivity of DQM, enabling the study of exotic transport and magnetic phenomena in emerging quantum materials. In this talk, I will present how I used the QuTip Python Libary to simulate NV spin dynamics for Optically Detected Magnetic Resonance (ODMR) measurements, and how I modelled decoherence and dephasing in Ramsey interferometry experiments. The results improved our understanding of ODMR images and prepared for implementing Ramsey and Hahn Echo pulse sequences. As a case study, I will discuss our investigation of superconducting currents in thin film type-II superconductor NbSe2. Using our scanning NV magnetometer, we reconstructed high-resolution images of superconducting vortices, extracted thickness-dependent effective screening lengths, and observed a disordered superconducting vortex glass. Notably, we also observed complex vortex-edge interactions where vortices were selectively pinned to one side of a step in material thickness. The results highlight the potential of DQM as both a diagnostic and exploratory tool for probing complex superconducting systems at the nanoscale.