Nonlinear optical molecular spectroscopy with quantum light and in microcavities

Nonlinear optical signals induced by quantized light fields and entangled photon pairs are predicted. Conventional nonlinear spectroscopy uses classical light to detect matter properties through the variation of its response with frequencies or time delays. Quantum light opens up new avenues for spectroscopy by utilizing parameters of the quantum state of light as novel control knobs and through the variation of photon statistics by coupling to matter. Novel signals are expressed using time-ordered multipoint correlation functions of superoperators in the joint field plus matter phase space. These are distinct from Glauber’s photon counting formalism which uses normally ordered products of ordinary operators in the field space. Entangled-photon pairs are not subjected to the classical Fourier limitations on their joint temporal and spectral resolution.

Crossings of electronic potential surfaces in nuclear configuration space, known as conical intersections, determine the rates and outcomes of virtually all photochemical molecular processes. Strong coupling of molecules to the quantum vacuum field of micro cavities which can be used to manipulate their photophysical and photochemical reaction pathways and polariton relaxation in photosynthetic antennae are demonstrated.