Abstract: At QET Labs, University of Bristol, we develop hybrid quantum interfaces for advanced networking, imaging, sensing, and computing. This talk overviews these efforts, focusing on recent advances in molecular spectroscopy leveraging optical interference. Molecules play diverse roles—from contributing to climate change to serving as catalysts and photon sources in quantum technology—making their precise characterization essential. I will present three optical techniques: (1) nonlinear interference for mid-infrared molecular imaging and fast methane detection; (2) quantum interference using single organic molecules to probe photon coherence and molecule–environment interactions; and (3) coherent interference in nanophotonic waveguides to characterize molecule–device coupling. Together, these methods demonstrate new capabilities for molecular analysis using quantum and photonic technologies.