Develops second- and third-harmonic generation (SHG/THG) nonlinear optical microscopy to image collagen and other non-centrosymmetric structural proteins label-free in tissue, with applications to cancer diagnosis and fibrosis, pushing spatial/orientational resolution of structural imaging in intact tissue.

Research focuses on quantum dynamics and excited-state reactivity in biological and synthetic light-harvesting systems. Discovered long-lived quantum coherence in photosynthetic light-harvesting complexes (FMO, 2007). Develops 2D electronic spectroscopy techniques to probe excitonic transport, open quantum systems, and photochemical reaction dynamics on femtosecond timescales. Director NSF QuBBE; co-director Berggren Center for Quantum Biology and Medicine.

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.

Rao's group uses ultrafast (sub-20 fs) transient absorption and vibronic spectroscopy to study quantum-coherent energy and charge transfer processes in molecular and nanoscale semiconductor systems, most notably the quantum-coherent mechanism of singlet exciton fission, with applications to next-generation photovoltaics.