Quantum interferometric two-photon excitation spectroscopy

TL;DR

This paper introduces a quantum interferometric approach to two-photon excitation spectroscopy, leveraging quantum Fourier transform and N00N-states to enhance resolution and reduce photon flux, enabling single-shot measurements of complex energy structures.

Contribution

It presents a novel quantum interferometric protocol that simplifies two-photon spectral engineering and enhances excitation spectroscopy capabilities.

Findings

Overcomes spectral engineering challenges in two-photon excitation

Enables high-resolution, single-shot measurements

Potentially reduces photon flux for sensitive samples

Abstract

Two-photon excitation spectroscopy is a nonlinear technique that has gained rapidly in interest and significance for studying the complex energy-level structure and transition probabilities of materials. While the conventional spectroscopy based on tunable classical light has been long established, quantum light provides an alternative way towards excitation spectroscopy with potential advantages in temporal and spectral resolution, as well as reduced photon fluxes. By using a quantum Fourier transform that connects the sum-frequency intensity and N00N-state temporal interference, we present an approach for quantum interferometric two-photon excitation spectroscopy. Our proposed protocol overcomes the difficulties of engineering two-photon joint spectral intensities and fine-tuned absorption-frequency selection. These results may significantly facilitate the use of quantum interferometric spectroscopy for extracting the information about the electronic structure of the two-photon excited-state manifold of atoms or molecules, in a "single-shot" measurement. This may be particularly relevant for photon-sensitive biological and chemical samples.