Clock synchronization with single photons

This thesis addresses the critical issue of clock synchronization in quantum communication systems. While quantum communication offers unmatched security, it demands precise timing, often achieved through resource-intensive methods. This study introduces a postprocessing protocol that eliminates the need for additional synchronization mechanisms in the sender, seamlessly integrating with existing quantum communication setups. The protocol exhibits exceptional performance, achieving timing stability down to 3 ps with simple crystal oscillators. Its robustness is demonstrated in real-world scenarios, including turbulent free-space and intercity links, where femtosecond-level stability is achieved. This versatile approach supports various single-photon sources, advancing quantum communication and secure time transfer technologies.