Overview

• The experiment achieved quantum key distribution (QKD) over 254 kilometers of standard fiber-optic cables between Frankfurt, Kehl, and Kirchfeld in Germany.
• This marks a new record for QKD distance in a practical telecom network, maintaining quantum coherence without cryogenic cooling.
• The study showcased the use of existing commercial fiber infrastructure, eliminating the need for specialized cables or extreme environmental controls.
• Researchers preserved fragile quantum states under operational conditions, addressing challenges like noise and temperature fluctuations in real-world networks.
• The techniques developed are expected to extend QKD distances further and support other quantum communication protocols, advancing the vision of a scalable quantum internet.