Achieving two-dimensional optical spectroscopy with temporal and spectral resolution using quantum entangled three photons

TL;DR

This paper demonstrates a novel two-dimensional optical spectroscopy method using entangled three photons, achieving high temporal and spectral resolution without Fourier limitations, suitable for complex molecular systems.

Contribution

It introduces a new spectroscopic measurement technique combining entangled three photons with frequency-dispersed two-photon counting, enhancing resolution and selectivity.

Findings

The method provides the same information as coherent 2D spectra.

Spectral distribution acts as a frequency filter for specific regions.

The technique is effective for complex molecular systems with narrow energy ranges.

Abstract

Recent advances in techniques for generating quantum light have stimulated research on novel spectroscopic measurements using quantum entangled photons. One such spectroscopy technique utilizes non-classical correlations among entangled photons to enable measurements with enhanced sensitivity and selectivity. Here, we investigate spectroscopic measurement utilizing entangled three photons. In this measurement, time-resolved entangled photon spectroscopy with monochromatic pumping [J. Chem. Phys. 153, 051102 (2020).] is integrated with the frequency-dispersed two-photon counting technique, which suppresses undesired accidental photon counts in the detector and thus allows one to separate the weak desired signal. This time-resolved frequency-dispersed two-photon counting signal, which is a function of two frequencies, is shown to provide the same information as that of coherent two-dimensional optical spectra. The spectral distribution of the phase-matching function works as a frequency filter to selectively resolve a specific region of the two-dimensional spectra, whereas the excited-state dynamics under investigation are temporally resolved in the time region longer than the entanglement time. The signal is not subject to Fourier limitations on the joint temporal and spectral resolution, and therefore, it is expected to be useful for investigating complex molecular systems in which multiple electronic states are present within a narrow energy range.