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

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 χ Y Y Y and χ XY Y nonlinearities, but also to higher-order χ (Y Y Y )(XY Y ) and χ (XY Y )(Y Y Y ) nonlinearities. Using quantum mechanical studies of the rhenium complex [Re(OH) 3 (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 C = 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.