Freiburg 2019 – wissenschaftliches Programm

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FM: Fall Meeting

FM 31: Secure Communication & Computation II

FM 31.6: Talk

Dienstag, 24. September 2019, 15:30–15:45, 1009

Simulation of generation and transmission of photons from SPDC for quantum key distribution with phase-time coding — •Julian Nauth, Erik Fitzke, Alexander Sauer, Gernot Alber, and Thomas Walther — TU Darmstadt, Institute of Applied Physics, 64289 Darmstadt

We are working on a QKD system with phase-time coding. A source generates entangled photons which are measured by the parties to generate a secure key. In theory, the influence of a potential hacker is detected by determining the quantum bit error rate. In practice, however, these errors may also be caused by the effects of real-world component properties and environmental influences. Therefore, we developed a simulation to estimate these influences.

The simulation is a quantum mechanical description of the generation and transmission of photons modeling the states of the system and the processes that change these states. Modeling is based on a multi-mode Gaussian state description of the states and the SPDC is calculated by Schmidt decomposition. The description in frequency space allows to model effects by the spectral distribution of the photons and chromatic dispersion.

Finally, the simulation predicts how the results of the detectors from the parties correlate at different times. On this basis, the assessment of the security of the key can be improved. We present the methodology and structure of the software and compare the calculations to experimental results.