Description: Combines STM's atomic spatial resolution with ESR's high energy resolution to coherently address and read out individual electron and nuclear spins on surfaces.
Loth combines ESR-STM with ultrafast terahertz-driven STM to read out and control individual atomic and molecular spins with atomic spatial and picosecond temporal resolution - single-spin quantum sensing at the ultimate spatial limit. In the broader landscape of NV-centre ensemble quantum sensing (DEER, nano-NMR, T1 relaxometry) operating near pT/sqrt(Hz) sensitivity, this work pushes spin sensing to the single-atom, ultrafast regime.
Otte's group pioneered electron-spin-resonance scanning tunneling microscopy (ESR-STM), positioning individual atoms one-by-one with a low-temperature STM tip and using all-electrical RF driving to coherently control and single-shot read out individual electron and nuclear spins (e.g., single 49Ti nuclei) with sub-neV energy resolution and atomic spatial resolution. Where NV-ensemble sensing reaches pT/sqrt(Hz) at the nanoscale, Otte's ESR-STM instead reaches the ultimate single-atom limit of magnetic sensing and quantum control, and the lab is developing a next-generation 15 T / 20 mK STM to push coherence times and energy resolution further.
Rogge (formerly Delft) works on the spectroscopy of individual dopant atoms in silicon: using transport, STM and microwave spectroscopy to read out the orbital, valley and spin structure of single donors and acceptors, including their coupling to strain, electric fields and each other. The group has mapped the wavefunctions of individual dopants and used acceptor spin-orbit coupling for electric-field-driven spin control. This is single-quantum-object measurement rather than device engineering. Positioned against the established body of NV-ensemble quantum sensing work — DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity — single-donor spectroscopy is the silicon analogue of single-NV work: the same questions about coherence, bath engineering and readout fidelity that fix pT/sqrt(Hz) ensemble performance appear here in a platform where the sensor can be placed with atomic precision and interrogated electrically rather than optically.