Rebecka Sax

To enable the widespread use of Quantum Key distribution, network integration is crucial. We present a case study where we investigate the performance of a 2.5 GHz simplified BB84 implementation using a wavelength of 1310nm multiplexed in a fiber together with 13 classical channels. We found that a secret key exchange at a distance of 95.5km and classical launch power up to 8.9dBm was possible. Further, we compare our results to previous results, both for continuous variable systems using a wavelength of 1550nm and discrete variable systems using either a wavelength of 1550nm or 1310nm. We find that both for long distance and for high power in the classical channels, the discrete variable systems perform better.

With the maturity of Quantum Technologies, namely Quantum Key Distribution (QKD) and Quantum Random Number Generation (QRNG), there has been mounting interest in scalable and inexpensive solutions for both academia and industry. To address the practicality and security requirements for QRNGs, we are developing a self-testing QRNG system based on homodyne detection with a fully integrated optical set-up. We use an Indium Phosphide (InP) photonic integrated circuit (PIC) with a high-speed 2.5GHz phase modulation that was designed and developed in collaboration with HHI Fraunhofer. All optical components are integrated in a 12×10 mm2 chip. It is then glued to a PCB designed in-house with electrical connections to the chip for full control and read-out of the results of the homodyne measurements. Another PCB, also designed in-house, is used to interface between the PIC and a field-programmable gate array (FPGA), which determines the quantum states to be prepared and reads out the homodyne detection. A graphics processing unit (GPU) connected to the FPGA then performs the statistical analysis of the data. The system operates at 1.25GHz and extraction rates above 18% are expected.