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.
Morello heads the Fundamental Quantum Technologies Laboratory and is the person who first read out the spin of a single electron, and then a single nucleus, in silicon. Current directions: high-spin donors (antimony-123, with eight nuclear levels) used as qudits and as sensors of local strain and electric field; nuclear acoustic resonance, in which a strain wave rather than a magnetic field drives the nuclear spin; engineered decoherence experiments as tests of quantum foundations; and precision tomography of multi-qubit donor registers. The group's donors are among the longest-coherence solid-state spins known (seconds for nuclei). 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 — a single-donor nuclear spin in silicon is functionally an NV centre with better coherence and worse readout: the same DEER, dynamical-decoupling and nuclear-register protocols apply, and the group's high-spin qudit work is aimed at exactly the multi-level sensing enhancements that the NV community is now chasing. Preferred attribute present: sensitivity and coherence, not fabrication, are the limiting variables here.
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.
Rahman does large-scale atomistic modelling of semiconductor quantum devices: tight-binding and DFT calculations of donor and quantum-dot wavefunctions, valley physics, spin-orbit coupling, hyperfine interactions and the response of all of these to strain and electric field, at system sizes large enough to represent a real device. The group works hand-in-glove with the Morello, Dzurak, Simmons and Rogge experiments, and increasingly uses machine learning to invert measurements into structural information. 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 — the same first-principles machinery is what predicts the hyperfine and spin-bath environment that determines T2 — and therefore the achievable pT/sqrt(Hz) sensitivity — of any solid-state spin sensor, including NV. Computational PI; would suit a candidate wanting a theory/experiment bridge role.
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.
Simmons pioneered atomic-precision fabrication in silicon: hydrogen-resist STM lithography, phosphine dosing and epitaxial silicon overgrowth to place individual dopant atoms with sub-nanometre accuracy, then measure them at millikelvin. The programme has produced single-atom transistors, precision dopant arrays used as analogue quantum simulators, and the largest atom-scale device platform in the world; she also founded Silicon Quantum Computing Pty Ltd. The sensing-relevant capability is the single-electron transistor as an exquisitely sensitive electrometer, capable of resolving individual charge transitions and mapping local electrostatic potential at the atomic scale. 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 — her SET electrometry is the charge-domain counterpart to magnetic NV sensing at pT/sqrt(Hz): both are single-quantum-object detectors whose performance is limited by back-action and by the noise of the readout chain. Very large group, strongly fabrication-oriented and commercially entangled, which cuts against the stated preference for sensitivity-limited rather than fabrication-limited work.