SEQUIN

SEQUIN — short for “Secure Use of Quantum Communication in Applications” — is a BMBF-funded German research project running from August 2024 to July 2027, with a total project volume of €3.25 million, of which €2.61 million is provided as BMBF funding.

The project focuses on significantly improving the side-channel resistance of CV-QKD (Continuous Variable Quantum Key Distribution) modules. Based on mathematical security analyses and experimental investigations, the research team works to uncover discrepancies between theoretical models and real-world implementations, identifies resulting potential attack vectors, and derives appropriate countermeasures.

On the hardware side, a central objective concerns the circuit concept and PCB design for transmitters and receivers, with suitable components and interfaces being selected to enable smooth and reliable data transmission. A key milestone in this context is the definition of interfaces to the QKD transmit and receive components of the project partners. Furthermore, a Security Orchestrator is being developed as the central control unit of the system, enabling the integration of various security mechanisms and protocols. Its development is based on a RISC-V processor core from Fraunhofer IPMS, which can be deployed platform-independently across various FPGAs.

A particularly critical hardware contribution within SEQUIN comes from Microwave Photonics GmbH, which is responsible for the development of a Dual-Polarization I/Q Coherent Receiver. This component represents a significant step beyond the single-channel architecture explored in DE-QOR: by simultaneously processing both polarization states of the optical signal across in-phase (I) and quadrature (Q) components, the receiver enables far greater sensitivity, noise resilience, and key rate performance. It is precisely this type of advanced receiver hardware that is essential for closing the gap between theoretical CV-QKD security models and practical real-world implementations — making Microwave Photonics’ contribution central to SEQUIN‘s core objective of achieving side-channel-resistant quantum communication.