Unfortunately, this seems to be behind a paywall.   https://www.computing.co.uk/ctg/news/2476096/china-to-complete-first-stretch... China to complete first stretch of dedicated 'quantum' encryption fibre network next month 2,000km network to provide foundation for secure quantum key distribution     * Graeme Burton     * @graemeburton    China to complete first stretch of dedicated 'quantum' encryption fibre ... 2,000km network to provide foundation for secure quantum key distribution,Security ,security,Cloud Computing   at is untappable by foreign intelligence services. The fibre... [end of quote] Jim Bell's comments follow: My isotope-modified optical fiber will greatly improve the practice of using such 'untappable' fibers, because the length of those links are generally limited by the fact that they cannot use the usual EDFA (Erbium-Doped Fiber Amplifiers).  https://en.wikipedia.org/wiki/Optical_amplifier    Current optical fibers are limited to about 0.150 dB/kilometer loss.  (See Corning Optical Communications; Sumitomo Electric Lightwave, etc.) The current link limit for quantum fibers is about 50 kilometers.   https://www.osa-opn.org/home/newsroom/2019/september/a_50-km_quantum_transmi... My fiber should have a loss 100x lower than today's fibers, so that the maximum link distance should be at least 5000 kilometers, which by a happy coincidence is the distance between New York and Ireland,   And the distance between Los Angeles and Hawaii is about 3800 kilometers.       https://daltonium.com/    The patent: http://freepatentsonline.com/9459401.html              Jim Bell