Polarization entanglement of sum-frequency photons: A tool to probe the Markovian limit

Abstract

The article addresses the possibility of entanglement-specific infrared-visible sum-frequency generation spectroscopy. In the case of an anisotropic interface, it is possible to employ SSS and PSS polarizations to detect responses not only specific to ${\ensuremath{\chi}}_{YYY}$ and ${\ensuremath{\chi}}_{XYY}$ nonlinearities, but also to higher-order ${\ensuremath{\chi}}_{(YYY)(XYY)}$ and ${\ensuremath{\chi}}_{(XYY)(YYY)}$ nonlinearities. Using quantum mechanical studies of the rhenium complex $[\mathrm{Re}{(\mathrm{OH})}_{3}{(\mathrm{CO})}_{3}]$ as a molecular model, we demonstrate that if such complexes would form an anisotropic orientational distribution at a surface, under the considered geometry and the polarization settings, we may prepare quantum correlated $\mathrm{C}=\mathrm{O}$ vibrational states to emit polarization-entangled photons. Accordingly, we explore the possibility of a polarization-measurement protocol to extract spectral signatures of the entangled states. The response would be informative on intramolecular interactions. As a result, we discuss the possible practical implications in probing dynamics at interfaces, and different opportunities in the preparation of entangled vibrational states of quantified fidelity.