Quantum light–matter interactions underpin the next generation of high-precision spectroscopy, imaging, and quantum photonics. We investigate these interactions along two complementary directions: (1) developing optical spectroscopies based on path- and energy-entangled photons to probe how quantum light couples to matter, and (2) exploring condensed-phase dynamics at the ultimate limits of single optical emitters, excitations, and photons. To this end, we develop spectroscopic methods that operate in the few-photon regime to study both the fundamentals of quantum light–matter interactions and the role of structural parameters in governing processes such as spin- and phonon-mediated dephasing of optical transitions. Our long-term goals are to establish quantum spectroscopy of materials and to improve solid-state single-photon emitters through a detailed mechanistic understanding of their current limitations due to detrimental system-bath interactions.

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