During the 3-year lifetime the project will develop the key components for quantum communication systems such as are used for true random number generation of secure-key distribution. UNIQORN follows a holistic approach whereby performance, effectiveness and efficiency are improved at each layer:
Starting with low layer components, the project will tailor existing mainstream photonic integration platforms like InP, CMOS and polymer photonic circuitry in order to advance their functionalities into the quantum regime. The InP integration will focus on small, weak coherent-pulse, photon transmitters and also on improved balanced receivers for detection of continuous variables quantum states which do not require single photon detectors. Avalanche Photo diodes (SPAD), capable of detecting single photons, will also be tailored to interconnect with the polymer platform to combine photon generation and detection on a single chip. Not only the efficiency of detection will be increased but also the pixel count. Such arrayed SPADs (1x4 and 4x4) are suited for photon-number resolution applications like Quantum Random Number generation and multi-photon demonstrations.
Those System-on-chip (SoC) integrations will be an essential part of the research work and will lead to highly miniaturized quantum-optic systems that will unleash the potential of quantum mechanical features such as entanglement and light squeezing. For photon-pair production, non-liner crystals will be accommodated by slots on the polymer platform. Together with the integrated SPADs, sub-components like headed single-photons sources or novel up-conversion detectors, where single photons at 1550nm are converted to 630nm for more efficient detection, will be realised.
To allow for seamless integration of the components into quantum applications like quantum key distribution, quantum oblivious transfer or squeezed state generation, the SoCs will be packaged with a fiber pigtail and all necessary signal generation electronics, reducing complexity and cost for field deployment.
Finally, selected systems are evaluated in the Bristol-is open smart city demonstrator. For this real-world test special quantum applications will be designed. For example, “one-to-many QKD” where many (cheap) transmitters link up to a central receiver hub, simulating a QKD access network. Furthermore, programable entanglement distribution is showcased, whereby active entanglement sharing between many users in a network is actively controlled using reconfigurable optical add-drop multiplexer.