Stimulated Raman Spectroscopy with Entangled Light; Enhanced Resolution and Pathway Selection

TL;DR

This paper introduces a femtosecond stimulated Raman spectroscopy method using entangled photons and interference detection to improve resolution and enable pathway selection, offering better temporal resolution of molecular dynamics.

Contribution

It combines entangled photon pairs with interferometric detection in FSRS, allowing pathway-specific measurements and enhanced resolution over traditional techniques.

Findings

Enables separate measurement of Raman gain and loss signals.

Provides improved temporal and spectral resolution for excited state dynamics.

Demonstrates advantages over classical and disentangled light sources.

Abstract

We propose a novel femtosecond stimulated Raman spectroscopy (FSRS) technique that combines entangled photons with interference detection to select matter pathways and enhance the resolution. Following photo excitation by an actinic pump, the measurement uses a pair of broadband entangled photons, one (signal) interacts with the molecule together with a third narrowband pulse induces the Raman process. The other (idler) photon provides a reference for the coincidence measurement. This interferometric photon-coincidence counting detection allows to separately measure Raman gain and loss signals, which is not possible with conventional probe transmission detection. Entangled photons further provide a unique temporal and spectral detection window that can better resolve fast excited state dynamics compared to classical and correlated disentangled states of light.