Pubblicato in: Armamenti, Cina

Cina. Ha lanciato un satellite che gestisce una rete globale di comunicazioni quantistiche.

Giuseppe Sandro Mela.

2022-08-12.

Banca Centrale Cina

«QUESS has enormous prospects in the defence sphere»

«The mission cost was around US$100 million in total»

Sicuramente la entità degli investimenti produce arricchimento scientifico, ma nulla vicaria la potenza della intelligenza umana lasciata libera di pensare.

La intelligenza è il vero patrimonio di un popolo. Intelligenti si nasce, non lo si diventa.

Ma la collettività riesce ad identificare e a far crescere la intelligenza solo ed esclusivamente se è anche essa intrinsecamente libera e sostanzialmente meritocratica, come lo è la Cina.

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La distribuzione a chiave quantistica (in sigla QKD, dall’inglese: Quantum key distribution) è un sistema della meccanica quantistica per garantire comunicazioni sicure. Abilita due parti a produrre e condividere una chiave segreta casuale solamente tra di loro che potranno usare per cifrare e decifrare i loro messaggi. Spesso, è chiamata impropriamente crittografia quantistica, poiché è l’esempio meglio conosciuto tra le operazioni di crittografia quantistica. Un’importante e unica proprietà della distribuzione quantistica è la capacità dei due utenti in comunicazione di rilevare la presenza di una terza parte che tenta di ottenere informazioni sulla chiave, dovuto al fatto che un processo di misura in un sistema quantistico in generale disturba il sistema.

La sicurezza della distribuzione a chiave quantistica si affida sui fondamenti della meccanica quantistica rispetto al tradizionale protocollo di distribuzione a chiave che si affida sulla difficoltà computazionale di certe funzioni matematiche, e non può fornire alcuna indicazioni al riguardo di possibili intercettazioni. La distribuzione a chiave quantistica è usata solo per produrre e distribuire la chiave, non per trasmettere qualsivoglia messaggio. La chiave può essere usata con qualsiasi algoritmo di cifrazione e decifrazione, che trasmetterà poi il messaggio su un canale di comunicazione standard. L’algoritmo più comunemente associato a questa chiave è il cifrario di Vernam. I sistemi commerciali esistenti ad oggi di distribuzione a chiave quantistica sono specificatamente pensati per governi e imprese con alti requisiti di sicurezza.

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«Quantum Experiments at Space Scale, QUESS, is a Chinese research project in the field of quantum physics. Tiangong-2 is China’s second Space Laboratory module which was launched on 15 Sep 2016. Tiangong-2 carries a total of 14 mission  and experiment packages, including Space-Earth quantum key distribution and laser communications experiment to facilitate space-to-ground quantum communication. A satellite, nicknamed Micius or Mozi after the ancient Chinese philosopher, is operated by the Chinese Academy of Sciences.

QUESS is a proof-of-concept mission designed to facilitate quantum optics experiments over long distances to allow the development of quantum encryption and quantum teleportation technology. Quantum encryption uses the principle of entanglement to facilitate communication that can absolutely detect whether a third party has intercepted a message in transit thus denying undetected decryption. By producing pairs of entangled photons, QUESS will allow ground stations separated by many thousands of kilometres to establish secure quantum channels. QUESS itself has limited communication capabilities: it needs line-of-sight, and can only operate when not in sunlight. The mission cost was around US$100 million in total. QUESS has enormous prospects in the defence sphere. The satellite will provide secure communications between Beijing. China is aiming to achieve the capability to counter the use of enemy space technology. The launch put China ahead of rivals, and brought them closer to hack-proof communications.» [Fonte]

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La Cina ha lanciato mercoledì un nuovo satellite quantistico che potrebbe essere il primo passo verso la creazione di una rete di comunicazione ultra-sicura con copertura globale. Si tratta di uno dei sei satelliti lanciati intorno a mezzogiorno dal razzo a risposta rapida Lijian dal centro di lancio satellitare di Jiuquan, nel deserto del Gobi. È uno dei sei satelliti lanciati intorno a mezzogiorno dal razzo a risposta rapida Lijian dal centro di lancio satellitare Jiuquan nel deserto del Gobi. Una rete di chiavi quantistiche utilizza particelle entangled per criptare un messaggio. Qualsiasi tentativo di furto o decodifica altera fisicamente il messaggio e allerta il destinatario, grazie alla legge della fisica quantistica. Chiamato Jinan 1, pesa meno di 100 kg.

Jinan 1 entrerà in servizio dopo un mese di test ed è solo il primo passo. Altri satelliti di questo tipo saranno lanciati nel prossimo futuro per supportare la comunicazione quantistica per oltre 100 utenti in tutto il mondo. t è anche un passo importante. La Cina è il primo Paese al mondo a realizzare la distribuzione di chiavi quantistiche in tempo reale, da satellite a terra, con un micro-satellite e stazioni terrestri miniaturizzate.

Mentre i satelliti di comunicazione tradizionali servono principalmente come relè, il compito più importante di un satellite quantistico è quello di generare particelle entangled da utilizzare come chiavi quantistiche. Queste chiavi quantistiche potrebbero diventare una risorsa preziosa per la comunicazione globale.

Nel maggio 2020 è iniziato un esperimento da record, condotto da un’altitudine di 36.000 km, ovvero 60 volte più in alto dell’orbita di Mozi, ha scritto Sun in un articolo pubblicato sul Chinese Journal of Astronautics nel luglio dello scorso anno. L’esperimento è stato apparentemente interrotto dopo che il satellite è stato avvicinato da un satellite di sorveglianza spaziale statunitense.

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«China launched a new quantum satellite on Wednesday that could be a first step towards establishing an ultra-secure communications network with global coverage. It was one of six satellites launched around noon by the Lijian quick response rocket from the Jiuquan Satellite Launch Centre in the Gobi Desert. It was one of six satellites launched around noon by the Lijian quick response rocket from the Jiuquan Satellite Launch Centre in the Gobi Desert. A quantum key network uses entangled particles to encrypt a message. Any attempt to steal or decode will alter the message physically and alert the receiver, thanks to the law of quantum physics. Called Jinan 1, it weighs less than 100kg.»

«Jinan 1 would enter service after a month of testing and it was “just the first step”. More such satellites would be launched in the near future to support quantum communication for more than 100 users around the globe. t is also an important step. It makes China the first country in the world to achieve real-time, satellite-to-ground quantum key distribution with micro-nano satellite and miniaturised ground stations»

«While traditional communication satellites mainly serve as a relay, the most important job of a quantum satellite is to generate entangled particles to be used as quantum keys. Those quantum keys could become a valuable resource for global communication»

«A record-breaking experiment began in May 2020, conducted from an altitude of 36,000km – or 60 times higher than Mozi’s orbit, Sun wrote in a paper in the Chinese Journal of Astronautics in July last year. The experiment was apparently paused after the satellite was approached by a US space surveillance satellite»

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China launches new satellite in ‘important step’ towards global quantum communications network

– Jinan 1 will conduct key distribution experiments in lower-Earth orbit after a month of testing

– More launches planned for near future to support quantum communication for over 100 users

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China launched a new quantum satellite on Wednesday that could be a first step towards establishing an ultra-secure communications network with global coverage.

It was one of six satellites launched around noon by the Lijian quick response rocket from the Jiuquan Satellite Launch Centre in the Gobi Desert, according to Xinhua.

The quantum satellite, developed by the Chinese Academy of Sciences, would conduct quantum key distribution experiments in lower-Earth orbit, the report said.

A quantum key network uses entangled particles to encrypt a message. Any attempt to steal or decode will alter the message physically and alert the receiver, thanks to the law of quantum physics.

It is the second quantum satellite launched by China after it sent the world’s first such satellite, Mozi, into orbit in August 2016.

Called Jinan 1, it weighs less than 100kg – about a sixth of the weight of Mozi – but can generate quantum keys at speeds two or three magnitude higher, the project team said in a statement posted on WeChat.

It said Jinan 1 would enter service after a month of testing and it was “just the first step”. More such satellites would be launched in the near future to support quantum communication for more than 100 users around the globe.

“It is also an important step. It makes China the first country in the world to achieve real-time, satellite-to-ground quantum key distribution with micro-nano satellite and miniaturised ground stations,” the statement said.

China’s first quantum satellite, Mozi, is equipped with what was the most sensitive device when it went into orbit six years ago – it can produce and detect a single photon, or an extremely weak particle of light. The satellite has conducted record-breaking experiments in quantum physics, including proving the feasibility of quantum communication from one continent to another.

But researchers involved in the project say Mozi has its limits. The first generation of space-based quantum communication devices, for instance, can only establish a stable link with the ground at night because the sun produces so much noise that the light signals are drowned out. Also, the bandwidth for quantum key distribution – which is as small as dial-up – restricts communication to voice or low-resolution videos.

In recent years, the team – led by Pan Jianwei, a professor and executive vice-president of the University of Science and Technology of China in Hefei – has been working to find solutions to these problems. That includes developing new technologies to maintain quantum communication during the daytime and in bad weather, according to research papers published by the team.

Zhao Yongli, a professor at the Beijing University of Posts and Telecommunications who is not part of the Mozi team, wrote in a 2020 research paper that technological developments had prompted China to build a quantum satellite constellation to take high-speed, stable quantum communication around the globe

While traditional communication satellites mainly serve as a relay, the most important job of a quantum satellite is to generate entangled particles to be used as quantum keys. Those quantum keys could become a valuable resource for global communication in the future, according to Zhao, who works in the State Key Laboratory of Information Photonics and Optical Communications at the university.

He said the more quantum satellites in orbit, the more keys could be generated and sent to a “pool” for users with high security demands.

“The idea is to continuously generate quantum keys between each pair of connected nodes, and then store the keys in a quantum key pool” managed by a central agency in China, Zhao said in the paper published in Chinese peer-reviewed journal Radio Communications Technology.

“Low-Earth orbit (LEO) satellites have the advantages of small channel loss and low transmission delay. It is a more feasible way to use the networking of LEO satellites to build a quantum satellite constellation,” he said.

Zhao said China also planned to have quantum satellites in high-Earth orbit (GEO or geosynchronous orbit) where they could remain relatively stationary with the ground. He estimated that three such satellites could cover the entire planet.

There would be significant transmission loss, but Zhao said GEO satellites could “generate keys continuously at a lower rate” and send them to the pool.

He said the Mozi team had been working on technologies to improve the efficiency of satellite links – including developing larger receiving mirrors and more accurate targeting systems – aiming to increase the rate of key generation.

China has also been testing cutting-edge quantum telecoms technology on Shijian 20, its most advanced communication satellite, according to Sun Xiaojie, a senior engineer with the Quantum Engineering Research Centre at the China Aerospace Science and Technology Corporation in Beijing.

A record-breaking experiment began in May 2020, conducted from an altitude of 36,000km – or 60 times higher than Mozi’s orbit, Sun wrote in a paper in the Chinese Journal of Astronautics in July last year.

The experiment was apparently paused after the satellite was approached by a US space surveillance satellite, USA 271, in August 2020 and it moved away at speed, according to a report by US military website Breaking Defence.

Sun said in the paper that the experiment resumed in November but did not mention the encounter with the US satellite. She said the research suggested that the error rate of light signals from a geostationary satellite was between 2 and 8 per cent, which was “good enough for quantum key distribution”.