Title : Surface-enhanced stimulated Raman spectroscopy with squeezed photonic states
Abstract:
Recent advances in generating well-defined quantum states of light facilitate novel sensing applications and enhance established measurement and sensing techniques. Stimulated Raman spectroscopy (SRS), a measurement modality based on Raman scattering, can benefit from tuning the quantum properties of the pump and the Stokes pulses, or the properties of quantum states of the stimulating and the excitation fields. Another process that can greatly increase the SRS efficiency is field enhancement due to plasmon excitation in the surface regions of metal nanoparticles.
Here we present theoretical and computational investigations of stimulated Raman scattering involving squeezed states of light, introducing the concept of surface- and quantum-enhanced stimulated Raman scattering. Furthermore, expressions for the respective SRS transition rates are presented, and their dependence on the quantum states of the optical field is discussed, with particular emphasis on the squeezing parameters characterizing these states. For cases involving surface enhancement, classical computational electrodynamics is employed to guide the exploration of nanosystems that support plasmon excitations. Our results demonstrate that quantum-enhanced Raman scattering, as an example of the emerging field of quantum sensing, can significantly benefit from the interplay between squeezed light states and surface-enhanced mechanisms. In particular, the SRS transition rates show significant enhancement when both surface plasmon effects and quantum squeezing of the light fields are incorporated. The presented results contribute to building a stronger interface between quantum optics and surface-enhanced stimulated Raman spectroscopy. Combining these areas holds promise for enhancing the performance and sensitivity of Raman probes.
