Mainz 2026 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 44: Laser Technology and Applications

Q 44.6: Talk

Thursday, March 5, 2026, 12:15–12:30, P 2

Quantum-Correlated Biphotons for Two-Photon Absorption in Biomimetic Photoswitches — •Gonca Under and Oleg Kornilov — Max-Born-Straße 2A, 12489, Berlin, Germany

Spontaneous parametric down-conversion (SPDC) provides a reliable technique for generating quantum-correlated photon pairs, enabling various quantum sensing and spectroscopic applications. In this work, we demonstrate the generation and detection of biphotons produced via type-I SPDC and their characterization using a single-photon detection setup. The photon pairs are separated at a beam splitter and routed directly into two independent single-photon detectors, allowing coincidence-based identification of quantum-correlated events. After establishing the coincidence detection scheme, we couple the biphoton state into a single spatial mode to form a well-defined quantum optical probe intended for future two-photon absorption (TPA) experiments on novel biomimetic photoswitches. Owing to their non-classical correlations, such photon pairs can achieve two-photon excitation at optical powers significantly lower than classical limits, paving the way for sensitivity enhancements compared to classical illumination in quantum-enhanced spectroscopy.

Keywords: Spontaneous Parametric Down Conversion; Biphotons; Two Photon Absorption; Single Mode Coupling; Biomimetic Photoswitches