Editing Quantum key distribution (section)

==== Chinese networks ====
In May 2009, a hierarchical quantum network was demonstrated in [[Wuhu]], [[China]]. The hierarchical network consisted of a backbone network of four nodes connecting a number of subnets. The backbone nodes were connected through an optical switching quantum router. Nodes within each subnet were also connected through an optical switch, which were connected to the backbone network through a trusted relay.<ref>{{citation
| title=Field experiment on a robust hierarchical metropolitan quantum cryptography network
| first1=FangXing  | last1=Xu
| first2=Wei       | last2=Chen
| first3=Shuang    | last3=Wang
| first4=ZhenQiang | last4=Yin
| first5=Yang      | last5=Zhang
| first6=Yun       | last6=Liu
| first7=Zheng     | last7=Zhou
| first8=YiBo      | last8=Zhao
| first9=HongWei   | last9=Li
| first10=Dong     | last10=Liu
| journal=Chinese Science Bulletin
| volume=54
| issue=17
| pages=2991–2997
| date=2009
| doi=10.1007/s11434-009-0526-3
| bibcode=2009ChSBu..54.2991X  | arxiv=0906.3576| s2cid=118300112 }}</ref>

Launched in August 2016, the [[Quantum Experiments at Space Scale|QUESS]] space mission created an international QKD channel between China and the [[Institute for Quantum Optics and Quantum Information]] in [[Vienna]], [[Austria]] − a ground distance of {{convert|7500|km|mi|abbr=on}}, enabling the first intercontinental secure quantum video call.<ref name="IOP">{{cite news|url=http://physicsworld.com/cws/article/news/2016/aug/16/china-launches-world-s-first-quantum-science-satellite|title=China launches world's first quantum science satellite|author=Lin Xing|newspaper=Physics World|publisher=Institute of Physics|date=16 August 2016|access-date=17 August 2016|archive-date=1 December 2017|archive-url=https://web.archive.org/web/20171201030546/http://physicsworld.com/cws/article/news/2016/aug/16/china-launches-world-s-first-quantum-science-satellite|url-status=dead}}</ref><ref name="OeAW">{{cite web |url = http://www.oeaw.ac.at/en/events-communication/public-relations-communication/public-relations-communication/ausgewaehlte-oeaw-pressemeldungen/press-releases/first-quantum-satellite-successfully-launched/ |title = First Quantum Satellite Successfully Launched |date = 16 August 2016 |access-date = 17 August 2016 |website = Austrian Academy of Sciences |archive-date = 18 March 2018 |archive-url = https://web.archive.org/web/20180318054341/https://www.oeaw.ac.at/en/events-communication/public-relations-communication/public-relations-communication/ausgewaehlte-oeaw-pressemeldungen/press-releases/first-quantum-satellite-successfully-launched/ |url-status = dead }}</ref><ref name="Spacecom">{{cite web |last1=Wall |first1=Mike |title = China Launches Pioneering 'Hack-Proof' Quantum-Communications Satellite |url = http://www.space.com/33760-china-launches-quantum-communications-satellite.html |website=Space.com |publisher=Purch |access-date = 17 August 2016 |date=16 August 2016}}</ref> By October 2017, a 2,000-km fiber line was operational between [[Beijing]], [[Jinan]], [[Hefei]] and [[Shanghai]].<ref name="insidescience">{{cite web |url = https://www.insidescience.org/news/china-leader-quantum-communications |title = Is China the Leader in Quantum Communications? | author = Yuen Yiu | date=19 January 2018 |access-date=19 March 2018 |website=[[Institute of Electrical and Electronics Engineers|IEEE]]}}</ref> Together they constitute the world's first space-ground quantum network.<ref name="ieee">{{cite web |url = https://spectrum.ieee.org/china-successfully-demonstrates-quantum-encryption-by-hosting-a-video-call |title = China Demonstrates Quantum Encryption By Hosting a Video Call | author = Amy Nordrum |date=3 October 2017 |access-date=17 March 2018 |website=[[Institute of Electrical and Electronics Engineers|IEEE]]}}</ref> Up to 10 Micius/QUESS satellites are expected,<ref name="sciencenews">{{cite web |url = https://www.sciencenews.org/article/global-quantum-communication-top-science-stories-2017-yir |title = A quantum communications satellite proved its potential in 2017 | author = Jian-Wei Pan |date=3 October 2017 |access-date=19 March 2018 |website=[[Science News]]}}</ref> allowing a European–Asian [[Quantum network|quantum-encrypted network]] by 2020, and a global network by 2030.<ref name="Xinhua">{{cite news|url=http://news.xinhuanet.com/english/2016-08/16/c_135604287.htm |archive-url=https://web.archive.org/web/20160817155904/http://news.xinhuanet.com/english/2016-08/16/c_135604287.htm |url-status=dead |archive-date=17 August 2016 |title=China Focus: China's space satellites make quantum leap |author=huaxia|date=16 August 2016|access-date=17 August 2016|publisher=Xinhua}}</ref><ref name="PopSci">{{cite news|url=http://www.popsci.com/chinas-quantum-satellite-could-change-cryptography-forever|title=China's Quantum Satellite Could Change Cryptography Forever|author1=Jeffrey Lin |author2=P.W. Singer |author3=John Costello |date=3 March 2016|access-date=17 August 2016|newspaper=Popular Science}}</ref>