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Scientists just sent unhackable quantum keys across 120 kilometers
Scientists have taken a major step toward ultra-secure quantum communication by demonstrating a remarkably stable quantum encryption system that worked across more than 120 kilometers of optical fiber. Using tiny semiconductor quantum dots that emit single particles of light on demand, the team achieved one of the highest secure key rates yet for this type of technology while maintaining continuous operation for over six hours without manual adjustments.
The article mentions that the quantum key distribution worked over 120 kilometers, but it doesn't clarify whether this was the actual transmission distance or the distance between the quantum key exchange stations. If the latter, then the security advantage over classical systems might be less impressive than claimed, since classical encryption could theoretically be secured across similar distances using existing infrastructure.