QKD hardware on small satellites

Freiwang, Peter (2023): QKD hardware on small satellites. Dissertation, LMU München: Faculty of Physics

Abstract

Quantum Key Distribution (QKD) enables the exchange of secret keys by which, based on the laws of quantum physics, eavesdropping attempts can be detected and their maximum information can be determined. By using satellites equipped with QKD hardware and an optical communication terminal, fundamental limitations for fber based QKD networks regarding the distance between the communicating parties can be overcome. In this thesis, a compact and robust QKD sender module, which has been designed, built, and qualifed for the integration into the 3-unit (30 × 10 × 10 cm3) Cube-Satellite QUBE, is presented. The goal of QUBE is to test and verify the suitability of QKD senders based on two different technologies under real space conditions. Our sender implements the BB84 QKD protocol with polarization encoding of weak coherent pulses (WCPs). Its compactness and its low power consumption is reached by the usage of mostly passive micro-optical components. Colleagues of the MPL in Erlangen provide a further payload which features the phase encoding of WCPs based on photonic integrated circuits. The harsh environmental infuences in space (radiation, thermal cycles, vacuum) and the mechanical vibration loads during the rocket launch require considerable tests of the hardware, which were performed on devices identical to the ones later integrated as fight models in the satellite. Promising results were achieved, which for example show a good quality of the prepared polarization states and a low quantum bit error ratio (QBER) of only 2.2% of the light emitted by the fully integrated satellite.

• Item Type: Theses (Dissertation, LMU Munich)
• Keywords: QKD, quantum key distribution, quantum communication, satellite communication
• Subjects: 500 Natural sciences and mathematics; 500 Natural sciences and mathematics > 530 Physics
• Faculties: Faculty of Physics
• Language: English
• Date of oral examination: 28. April 2023
• 1. Referee: Weinfurter, Harald
• Signature of the printed copy: 0001/UMC 29908