Quantum Key Distribution Achieves 120 km Secure Transmission

• •First successful demonstration of time-bin encoded QKD using semiconductor quantum dots.
• •Achieved a secure key rate of approximately 15 bits/s over a 120 km fiber link.
• •System maintained stability for over six hours with quantum bit error rates below 11%.

An international team from Germany and China has successfully demonstrated quantum key distribution (QKD) using time-bin encoding and semiconductor quantum dots (SQDs) over a 120 km fiber link. This proof-of-concept experiment achieved the highest secure key rate reported for such systems, maintaining a secure key rate of approximately 15 bits/s with average quantum bit error rates below 11%. The system operated continuously for over six hours, showcasing its stability and robustness. The integration of SQDs with time-bin encoding represents a significant advancement in the field of quantum cryptography, paving the way for scalable QKD networks. The researchers emphasized the potential of telecom-band quantum dots for practical QKD applications in future quantum internet infrastructures.