-
StatusOngoing
-
Status date2025-03-10
-
Activity Code3D.028
The aim of the project is to define, develop and test an optical system for quantum key distribution (QKD) that's suitable for satellite links based on a multidimensional quantum state encoding protocol. The breadboard will consist of a transmitter and a receiver that implements encoding based on polarisation, time and frequency degrees of freedom of single photons, generated by parametric down-conversion.
The protocol aims to achieve a dimensionality of eight, with the potential to be extended to 16 dimensions, improving the security and efficiency of QKD systems in space applications.
The project's main challenge is using three different types of quantum information –polarization, time, and frequency – in a single photon. The most important and difficult part is making sure the photons remain in a coherent state for a long time. This is necessary to maximise the number of quantum information dimensions that can be used.
The proposed QKD system offers several key benefits, including optimised resilience against atmospheric turbulence, which potentially eliminates the need for adaptive optics, enhancing photon system detection efficiency.
The use of higher-dimensional quantum states for encoding enhances the quantum information link capacity, and the system leverages entangled photon pairs, allowing for measurement-device-independent (MDI) security, which mitigates vulnerabilities associated with detector side-channel attacks. These advantages contribute to the system's enhanced efficiency, security, and scalability when compared to conventional QKD solutions, positioning it as a robust platform for long-distance free-space quantum communication.
The proposed QKD system uses a protocol based on the well-established BBM92 scheme, ensuring proven security principles. It uses the parametric down-conversion process to generate hyper-entangled photon pairs, enabling encoding across multiple degrees of freedom, such as polarization, time, and frequency. In the system architecture, one photon is transmitted to the receiver via a free-space optical link, while the other photon is measured locally at the transmitter side.
The system architecture consists of a transmitter and a receiver de- signed for free-space quantum key distribution (QKD).The transmitter is based on a hyper-entangled photon pair generator and analyser, capable of encoding quantum information using polarization, time, and frequency degrees of freedom.
The receiver is equipped with an advanced photon state analyzer to measure the transmitted quantum states accurately. The system's performance in the presence of environmental disturbances will be assessed by testing the free-space optical link under realistic conditions using an atmospheric turbulence emulator.
Regular progress meetings will be held bi-weekly via teleconference, while key milestones such as the Preliminary Design Review (PDR), Detailed Design Review (DDR), Test Readiness Review (TRR), and Final Review/Presentation (FR/FP) will be scheduled according to the project timeline.
The project includes State of the Art (SotA) analysis, detailed design, implementation, and testing phases. The MAIT phase will span 10 months, verifying system performance. The project concludes with technology assessment, hardware/software delivery, and the Final Review.
The project has just commenced.
