Towards robust detection of entangled two-photon absorption

TL;DR

This paper demonstrates a robust method to detect entangled two-photon absorption (ETPA) effects at room temperature in low-flux regimes, addressing previous detection challenges and confirming ETPA's dependence on correlation area and cross-sections.

Contribution

It introduces a new scheme for evidencing ETPA that is resistant to artifacts like linear absorption and fluorescence, advancing experimental verification of entangled light-matter interactions.

Findings

ETPA effects observed at room temperature in organic and inorganic chromophores.

Detection scheme is robust against common artifacts such as linear absorption.

ETPA scales with transverse correlation area and two-photon cross-sections.

Abstract

Over the last 50 years entangled photon pairs have received attention for use in lowering the flux in two-photon absorption imaging and spectroscopy. Despite this, evidence for entangled two-photon absorption (ETPA) effects remain highly debated, especially at low-fluxes. Here, we structure the transverse spatial correlations of entangled photon pairs to evidence signs of ETPA at room-temperature in organic and inorganic chromophores, in the low-flux regime. We demonstrate our scheme to be robust to common artifacts that have previously hampered detection of ETPA such as linear absorption and background fluorescence, and show that ETPA scales with transverse correlation area and chromophore two-photon cross-sections. Our results present a step towards verifying ETPA and experimentally exploring entangled light-matter interactions.