James Dynes

Random numbers play a crucial role in information technology, particularly as digital communication capacity continues to expand. Consequently, the need for secure and high-rate random number generation has become increasingly urgent. While integrated photonics technology holds promise for mass-producing optoelectronic quantum random number generators (QRNGs), there remains a challenge in developing fast, robust, and scalable solutions suitable for industrial deployment. Addressing this challenge, we present a fast QRNG solution in this study, leveraging a photonic integrated circuit (PIC) directly embedded onto a versatile electronic platform. Designed to withstand real-world applications, our PIC is packaged to align with industrial electronic assembly lines. To rigorously assess scalability and stability, these generators underwent week-long periods of continuous GHz operation. Furthermore, a QRNG was integrated into a quantum key distribution system, where despite operating in an uncontrolled environment, minimal variations in physical randomness were observed over 38 days, as measured from 2.9 million histograms. Finally, we implemented a security model for the QRNGs, enabling rate adjustment to match the actual randomness content and demonstrating secure generation at 2 Gbit/s.

Quantum Communications (QC) harness quantum mechanical phenomena such as superposition and entanglement to enhance information transfer between remote nodes. Coherent quantum communications refer to QC schemes relying on maintaining optical coherence between nodes for successful execution. These schemes typically involve single photon interference between optical fields generated by distant parties and represent a cornerstone of a promising architecture of the quantum internet. Despite their significant potential, scientific and technical hurdles - including optical coherence maintenance, integrating high-performance single-photon detectors, and precise stabilisation and synchronisation - have prevented the implementation of coherent QC over existing telecommunication infrastructure. Here we present the first realisation of a coherent QC fully integrated into standard telecommunication infrastructure over a link connecting the German cities of Frankfurt and Kehl. The implemented scheme is the Twin Field Quantum Key Distribution (QKD) protocol, enabling the distribution of a shared secret key for encryption at a rate of 110 bit/s over a highly asymmetric 254 km link. This result, obtained with a system featuring measurement-device-independent properties, marks the longest installed QKD implementation utilising non-cryogenic cooled detectors and was enabled by the QC system architecture we developed and by our approach to phase stabilisation, which involves active out-of-band phase stabilisation and avalanche photodiodes for single photon detection. This achievement, not only represents a milestone for practical quantum communications but also validates the compatibility of coherent QC with current telecommunication infrastructure, supporting the feasibility of a phase-based architecture for the quantum internet.

Integrated photonics presents an opportunity for low-cost and highly-reproducible quantum cryptographic systems. However, due to numerous challenges such as packaging, power consumption and interfacing multiple chips in real, a standalone deployable photonic integrated system is still missing. Here we address all these challenges to present a real-time quantum communication system using integrated photonics. The system operated without intervention over multiple days and is capable of secure key rates of > 470 kbps over 10 km of fiber

We demonstrate the first experimental overcoming of the repeaterless secret key capacity (PLOB) bound through the implementation of the Twin Field Quantum Key Distribution (TF-QKD) protocol. We distribute secret keys at record channel losses (> 90 dB). We assess the prospects for real-world implementation of TF-QKD.

We developed a system for real-time transmission of genome sequence data using quantum cryptography and have succeeded in the quantum cryptography transmission of genome sequence data with data volumes exceeding several hundred gigabytes. This demonstrated that quantum cryptography can transmit large amounts of data and has practical applications in the fields of genomic research and genomic medicine.

Running single photon detectors (such as single photon avalanche photodiodes or superconducting nanowire detectors) at high speed is challenging and requires innovative driving and signal processing electronics. Self-differencing has been shown to be a very successful method to achieve detection rates in excess of 1 GHz using APDs while keeping low error rates from dark counts and afterpulses. Here, we present first results of high bit-rate QKD using a novel compact self-differencing setup which is integrated completely on a single printed circuit board (PCB). We achieve bit rates higher than 1 Mbit/s for a fibre distance of 50 km.