Degen leads the Spin Physics and Imaging group, one of the world's leading NV-center magnetometry labs. Research directions (as of 2025): (1) Scanning NV magnetometry of quantum materials — NV-tipped cantilevers image current flow (≲50 nm resolution) in graphene heterostructures and resolve domain walls in antiferromagnets/ferroelectrics; cryogenic scanning down to 350 mK in dilution refrigerator (published Appl. Phys. Lett. 2022). (2) Single-molecule NMR — shallow NV centers detect nuclear spins from surface-adsorbed molecules with sub-nanometer 3D resolution; 2022 Nano Lett. on amine-functionalized diamond surfaces; exploring chirality-induced spin selectivity at few-molecule level. (3) NV magnetometry protocols — reconstruction-free waveform sensing (1.1 ns time resolution, Nature 2025), gradiometric detection, spectrum demodulation for rapid scanning, multi-NV addressing. (4) Diamond nanoengineering — multicone pillar waveguides, surface engineering, scanning probe fabrication. ERC Proof-of-Concept 2025 for photonic IC single-photon NV excitation/detection for commercial quantum sensing.
Hollenberg is the intellectual centre of gravity for diamond quantum sensing in Australia: a theorist-turned-programme-leader whose group develops NV-based quantum probes for biological systems and quantum-computing architectures in silicon and diamond. Current directions include the quantum-probe hyperspectral microscope, in which NV ensembles in a bulk diamond substrate report magnetic and spin-noise contrast from cells cultured directly on the surface; nanodiamond quantum probes for intracellular relaxometry and free-radical detection; theory of decoherence-based sensing (T1 relaxometry as a chemical-specificity channel rather than a nuisance); and single-cell magnetic resonance. He co-leads the Melbourne node of the ARC Centre of Excellence in Quantum Biotechnology (QUBIC) with Simpson and Hinde, which is explicitly chartered to build quantum sensors for live biology, including portable brain imagers. 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 — his programme is one of the small number worldwide that has carried those ensemble protocols all the way into cell culture and tissue rather than stopping at proof-of-principle magnetometry. Preferred attribute present: the group's emphasis is on sensitivity and biological specificity rather than device fabrication, and QUBIC funding runs to 2030 with recurring postdoc recruitment.
Develops quantum sensing platforms at the biology interface. Core NV-center work: (1) widefield NV magnetic imaging of action potentials in neurons and cardiac tissue; (2) NV-based single-molecule NMR at 14 T resolving molecular structure with single-molecule sensitivity; (3) charge-sensitive shallow NV nanoprobes monitoring real-time cellular electrophysiology; (4) biocompatible diamond surface functionalization enabling multiplexed DNA microarray biosensing; (5) fluorescent-protein spin qubits as biological alternatives to diamond NV (2025 paper, Physics World Top-10 Breakthrough). Runs full NV stack: hot implantation, widefield and confocal ODMR, T1/T2/Hahn echo/DEER/Rabi, automated fitting pipelines. 2026 Sloan Fellow. PhD Lukin/Harvard; postdoc Chu/Stanford. Argonne joint appointment.
Simpson runs the experimental quantum imaging and sensing laboratory at Melbourne and is the closest match at this institution to a bio-oriented NV sensing postdoc. Two active threads: (i) widefield NV magnetic and spin-relaxation imaging of living cells and tissue, including magnetic imaging of magnetotactic bacteria, cellular free radicals and paramagnetic ion transport, and quantum-probe imaging of neuronal activity; and (ii) engineering Australia's most sensitive diamond vector magnetometer with RMIT and Phasor Innovation, aimed at navigation, underground/undersea sensing and, explicitly, mapping magnetic signals of the human brain in unshielded environments. That second thread is a direct bid at bioelectromagnetism with a quantum sensor. 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 — Simpson's work is a continuation of exactly that lineage, pushing ensemble DEER/T1-relaxometry contrast mechanisms out of the physics lab and into cell biology and human-scale magnetoencephalography. Preferred attributes present: bioelectromagnetism, human-subject ambitions, sensitivity-limited (not fabrication-limited) programme. QUBIC investigator; recruits postdocs regularly.