Develops computational methods (DFT + many-body perturbation theory, quantum embedding) to predict properties of spin defects for quantum sensing and computing. Directions: (1) first-principles prediction of coherence properties, zero-phonon lines, and spin-photon coupling for NV, SiC divacancy, Er, and other color center platforms; (2) high-throughput screening of novel spin defect candidates in 2D materials and oxides; (3) quantum embedding methods for strongly correlated defects. Director MICCoM; NAS member; Argonne senior scientist.

Kassal is the leading Australian theorist of quantum effects in light harvesting. He established the distinction between coherent processes and coherent states in photosynthesis — showing that under incoherent sunlight at steady state, wavelike motion per se does not enhance efficiency, while environment-assisted transport and supertransfer genuinely can — and has since developed a classification of the mechanisms by which coherence (excitonic, vibrational, or of the light field itself) can improve energy transport. He also pioneered quantum-computer algorithms for chemistry. A distinct and directly relevant thread is the theory of spectroscopy with non-classical light: what entangled or squeezed photons can reveal about molecular coherence that classical light cannot. 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 work is the theoretical counterpart to the quantum-biology ambitions of the NV community: where NV ensembles at pT/sqrt(Hz) try to detect the magnetic signatures of biological spin chemistry, Kassal asks what quantum coherence is actually doing in those systems and whether quantum light can interrogate it.

Olaya-Castro leads theoretical research on quantum phenomena in biological systems. Research directions: (1) Quantum coherence in photosynthesis — open quantum systems theory for energy transfer in light-harvesting complexes, probing whether quantum coherence provides functional advantage; vibronic coupling models for chromophore-protein complexes; (2) Counting statistics and noise in exciton and charge transfer; (3) Quantum thermodynamics of biomolecular machines — efficiency limits and entropy production in molecular motors; (4) Non-classical features of electronic/vibrational dynamics in chromophores; (5) Connections between quantum information measures and biological function. Collaborates with Bain and Llorente-Garcia on joint experiment/theory biosensing projects. Theoretical work only — no experimental activity.

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.