Quantum interferometric two-photon excitation spectroscopy

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 without any requirement for precise and complicated scanning in the spectral domain. This may be particularly relevant for photon-sensitive biological and chemical samples.

Does entanglement enhance single-molecule pulsed biphoton spectroscopy?

“…Experimentally, LOCC operations on continuous-variable (CV) time-frequency entangled states have been successfully implemented as part of CV teleportation of light states [63,64]. Our 1-LOCC detection scheme is thus a potentially attractive class of measurements for biphoton spectroscopy, and must be contrasted against interferometric quantum spectroscopies that propose global measurements by bringing together the two photons in linear [65,66] or non-linear interferometers [67] at the detection stage. Operationally, the idler-to-signal 1-LOCC detection scheme can also be viewed as a heralding scheme where a measurement is performed on the idler photon, and outcomes communicated to the signal station independently of the light-matter interaction which has support on the MSE subspace.…”