【Date and Time】10-March-2026 10:00 (Beijing time)

【Venue】Room 526

【Host】Ding Zhang (Tsinghua Univ.BAQIS)

【Title】 Free radical detection using nanodiamond quantum sensors

【Speaker】 

Dr. Ruoming Peng obtained his Ph.D. degree in electrical engineering from the University of Washington in 2022. He worked with Prof. Mo Li and studied exciton physics in 2D nanophotonic devices. After graduation, Ruoming spent a short period as the Kananoff-Rice postdoc fellow at the University of Chicago and then moved to the 3rd Institute of Physics at the University of Stuttgart under the supervision of Prof. Joerg Wrachtrup. Ruoming has developed strong expertise in 2D optical spectroscopy and quantum sensing. He is currently managing the scanning probe subgroup at the 3rd Institute of Physics and working on scanning quantum microscopy for emergent condensed matter phenomena.

【Abstract】

Electromagnetic interaction underlies emergent phases in solid-state systems, from magnetism and superconductivity to topological order. Yet probing these interactions at the nanoscale remains a major challenge for conventional techniques. In this talk, I’ll introduce the quantum sensing architecture we have developed by combining a quantum spin defect, a single NV center in diamond, with scanning probe microscopy. This approach offers ~30 nm spatial resolution and 1 μT/√Hz magnetic-field sensitivity, enabling us to probe local magnetic dynamics in quantum materials. As examples, I’ll first show how nanoscale quantum sensing reveals the super-Moiré magnetic order emerging in twisted antiferromagnets. By extending the sensor’s dynamic range through qubit coherence control, we can also access time-dependent behavior in 2D superconductors, where vortices remain mobile even far below the critical temperature. Looking ahead, I’ll discuss our recent progress toward a better quantum sensor by interfacing molecules with 2D materials. Here, we demonstrated the first optically addressable spin qubits at surfaces, that mitigate the dephasing common to near-surface defects, enabling direct NMR detection of protons and magnetic sensing of 2D materials. Together, I hope to convey a perspective on how quantum sensing can transform our ability to visualize, understand, and ultimately engineer quantum matter at surfaces.

[1]   Sreehari Jayaram, et al. "Probing Vortex Dynamics in 2D Superconductors with Scanning Quantum Microscope" Physical Review Letters, Editors’ Suggetions (2025)

[2]   King Cho Wong, et al. "Super-Moire Spin Textures in Twisted Antiferromagnets" Nature Nanotechnology, (2026)