Hannover 2020 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 39: Posters: Quantum Optics and Photonics III

Q 39.45: Poster

Wednesday, March 11, 2020, 16:30–18:30, Empore Lichthof

Photon Generation by Spontaneous Parametric Down Conversion for Quantum Key Distribution — •Julian Nauth, Alexander Sauer, Erik Fitzke, Gernot Alber, and Thomas Walther — Institut für Angewandte Physik, Technische Universität Darmstadt

We consider a source which generates entangled photons by spontaneous parametric down conversion (SPDC). After passing through a setup, the photons are measured by two parties to generate a secret key via a phase-time coding based quantum key distribution (QKD) protocol. As the requirements for the experimental components are highly demanding in this QKD setup, we aim to characterize the influence of imperfect devices, such that the resulting errors do not have to be attributed to a potential eavesdropper. We simulate the setup by modeling the states of the system as multimode Gaussian states which are transformed by each component of the setup. With this, SPDC and subsequent frequency- and polarization-dependent effects are modeled. The simulation yields the correlations of detection events for the parties at different times. We compare our calculations to experimental results and analyze the influence of different device imperfections on the correlations.