Entangled Photons Enabled Ultrafast Stimulated Raman Spectroscopy for Molecular Dynamics

Quantum entanglement has emerged as a great resource for interactions between molecules and radiation. We propose a new paradigm of stimulated Raman scattering with entangled photons. A quantum ultrafast Raman spectroscopy is developed for condensed-phase molecules, to monitor the exciton populations and coherences. Analytic results are obtained, showing a time-frequency scale not attainable by classical light. The Raman signal presents an unprecedented selectivity of molecular correlation functions, as a result of the Hong-Ou-Mandel interference. This is a typical quantum nature, advancing the spectroscopy for clarity. Our work suggests a new scheme of optical signals and spectroscopy, with potential to unveil advanced information about complex materials.