Bartholomew trained with Sellars (ANU) and Faraon (Caltech) and runs the Quantum Integration Laboratory, which works on rare-earth ions (erbium, europium, ytterbium) in crystals and in nanophotonic devices. Rare-earth ions have the longest optical and spin coherence times of any solid-state emitter, which makes them simultaneously the best optical quantum memories and, less obviously, extremely good sensors: the group works on rare-earth-based microwave and RF quantum sensing, on-chip integration of ions with photonic and superconducting circuits, and telecom-band spin-photon interfaces. 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 — rare-earth ensembles are the closest solid-state analogue to NV ensembles, with narrower optical lines and longer coherence but cryogenic operation; protocols like DEER and dynamical-decoupling-enhanced sensing at pT/sqrt(Hz) map across directly. This is one of the best fits at Sydney for a solid-state spin-sensing candidate.

Develops rare-earth-ion-doped crystal platforms for quantum internet hardware. Directions: (1) Er3+-doped crystal quantum memories with >1 ms coherence time in nanophotonic waveguides; (2) microwave-to-optical quantum transduction using Er spins coupled to superconducting resonators; (3) photon-number-resolving detectors for quantum communication; (4) integrated rare-earth nanophotonic circuits on thin-film LiNbO3. Key goal: scalable room-temperature-compatible quantum repeater nodes.