Project: Exploiting Entangled two-photon absorption

Acronym	E2TPA
Duration	01/05/2022 - 30/04/2025
Project Topic	Entangled two-photon absorption (ETPA) is a rapidly emerging technique for studying atoms and molecules, especially in low photon flux regimes. It has similarities to both classical single- and two- photon absorption techniques, which are cornerstones of modern optical imaging, but the quantum correlations, or photon-pair entanglement, also brings novel characteristics to investigate other physical regimes, e.g., in studying intermediate and virtual level transitions and dynamics. There is a long-standing theoretical basis and an increasing number of experimental demonstrations, although consistency between them currently remain. This project aims to fill these missing links. On the theory side we plan to develop a comprehensive quantum description of the light matter interaction for ETPA, allowing for better system design and application targeting. A limiting factor for current experiments is the signal-to-noise levels. We address this on the theory level, not only through a more complete model bridging conceptual approaches from quantum optics and physical chemistry where ETPA has been explored, but also designing nanoparticles for optimising excitation and collection efficiencies. On the experimental side, we will design and fabricate periodically poled lithium niobate sources for efficient broadband photon pair generation, as well as developing custom lasers, to improve ETPA rates. Experimentally, we have already demonstrated ETPA via fluorescence measurements and will further advance this, as well as develop a transmission-based correlation measurement scheme for complementary measurements. We will survey potential end- users and develop a toolkit to facilitate system design and describe the application potential for quantum-enhanced microscopy and quantum spectroscopy.
Network	QuantERA II
Call	QuantERA II Call 2021

Project partner

Number	Name	Role	Country
1	University of Geneva	Coordinator	Switzerland
2	Paderborn University	Partner	Germany
3	PicoQuant	Partner	Germany
4	Nicolaus Copernicus University	Partner	Poland
5	University College London	Observer	United Kingdom