SAMOP 2023 – scientific programme

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QI: Fachverband Quanteninformation

QI 23: Poster II (joint session QI/Q)

QI 23.25: Poster

Wednesday, March 8, 2023, 16:30–19:00, Empore Lichthof

Measurement of the phase-matching function in PPKTP waveguides — •Jan-Lucas Eickmann, Florian Lütkewitte, Kai-Hong Luo, Michael Stefszky, Laura Padberg, Harald Herrmann, and Christine Silberhorn — Paderborn University, Integrated Quantum Optics, Institute of Photonic Quantum Systems (PhoQS), Warburger Str. 100, 33098 Paderborn, Germany

Single-photon sources with high purity are a prerequisite for the development of practical photonic quantum computation. Spontaneous parametric down-conversion in periodically poled potassium titanyl phosphate (PPKTP) is a promising approach to generate spectrally pure quantum light by achieving a phase-matching function perpendicular to the pump function. However, the phase-matching function varies with the condition of waveguide fabrication and the quality of periodic poling. Therefore, a precise measurement of the phase matching dependence is crucial for integrated photonic quantum source engineering. In this work, we present a method for measuring the phase-matching function in PPKTP waveguides by exploiting sum-frequency generation. Using the measured phase-matching function, we reconstruct the joint spectral intensity (JSI) for different pump fields to assure the spectral purity of the heralded photon. We observe that the phase matching results in JSI functions with a tilt of around 60°, deviating 15° from a symmetric function required for optimum pure state preparation.