Mainz 2026 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 10: Quantum Technologies – Photon Detectors and Sources
Q 10.1: Vortrag
Montag, 2. März 2026, 17:00–17:15, P 5
Photon-number resolved characterization of a type-II SPDC light source — •Umair A. Mir1,2, Oskar Kohout1,2, Carlos Sevilla1,2, and Fabian Steinlechner1,2 — 1Institute of Applied Physics IAP, Friedrich Schiller University, Jena, Germany — 2Fraunhofer Institute of Applied Optics and Precision Engineering IOF, Jena, Germany
Squeezed light sources have become important resources for applications in quantum information processing areas. Spontaneous parametric down conversion (SPDC) is the most widely used method to generate squeezed states of light. In a type-II SPDC process, the signal and idler photons are orthogonally polarized, and when they are of the same wavelength, the output state corresponds to a two-mode squeezed vacuum (TMSV) state. The signal and idler modes are then perfectly correlated and entangled in the photon-number basis, which can be directly probed via joint photon statistics (JPS) measurements using a photon-number-resolving (PNR) detector. In this work, we measure JPS of type-II apktp and ppktp crystals serving as SPDC sources using a commercially available PNR detector with up to four photon resolution. From the measured statistics, we estimate the overall squeezing gain and transmission losses via a loss model that minimizes the deviation between simulated and experimental JPS, providing an alternative characterization method to conventional homodyne detection. Furthermore, we discuss how JPS measurements can offer insights into the spectral composition of more general SPDC-generated light, where each spectral mode corresponds to an independent TMSV state.
Keywords: Squeezed Light; SPDC; PNR