Theory of Quantum-Enhanced Stimulated Raman Scattering (2502.19344v1)

Abstract: Stimulated Raman scattering (SRS) is a powerful method for label-free imaging and spectroscopy of materials. Recent experiments have shown that quantum-enhanced Raman scattering can surpass the shot noise limit and improve the sensitivity substantially. Here, we introduce a full theory of quantum-enhanced SRS based on the framework of quantum metrology. Our results enable the assessment of quantum-enhancements of arbitrary measurement strategies and identify optimal measurement observables that extract maximal information about the signal. We use this to identify the optimal employment of squeezed states in SRS, highlighting the potential to improve quantum gains beyond those observed in recent experiments. Our work establishes the theoretical foundation for understanding and approaching the quantum limits of precision in SRS, and provide a tool to discuss nonlinear spectroscopy and imaging more broadly.