Quantum Breakthrough: Unhackable Keys Sent Over 120 km Using Quantum Dots

Researchers achieved a quantum key distribution (QKD) breakthrough by transmitting unhackable encryption keys over 120 kilometers using semiconductor quantum dots, marking the longest stable distance for this method. The advance leverages time-bin QKD with solid-state quantum dots, which generate high-quality non-classical photons—critical for secure quantum communication in future quantum networks. This milestone demonstrates practical performance in real-world conditions, addressing previous challenges like photon loss and decoherence over long fiber-optic distances. Quantum dots offer scalability and integration advantages over traditional QKD sources, potentially accelerating deployment in existing telecom infrastructure. The development strengthens the foundation for a quantum internet, where fundamentally secure communication could redefine cybersecurity for governments, finance, and critical infrastructure.