Nonlinear spectroscopy with entangled photons; manipulating quantum pathways of matter

TL;DR

This paper demonstrates how entangled photons can be used to selectively control quantum pathways in nonlinear spectroscopy, revealing new material information by manipulating quantum interference effects.

Contribution

It introduces a method to distinguish and control quantum pathways in nonlinear spectroscopy using entangled photon pairs, enabling pathway-selective measurements.

Findings

Entangled photons enable pathway selectivity in nonlinear spectroscopy.

Spectral overlap between SRS and TPA pathways can be resolved.

New material information can be accessed through quantum pathway manipulation.

Abstract

Optical signals obtained by the material response to classical laser fields are given by nonlinear response functions which can be expressed by sums over various quantum pathways of matter. We show that some pathways can be selected by using nonclassical fields, through the entanglement of photon and material pathways, which results in a different-power law dependence on the incoming field intensity. Spectrally overlapping stimulated Raman scattering (SRS) and two-photon-absorption (TPA) pathways in a pump probe experiment are separated by controlling the degree of entanglement of pairs of incoming photons. Pathway-selectivity opens up new avenues for mapping photon into material entanglement. New material information, otherwise erased by interferences among pathways, is revealed.