Researchers in Beijing have set a new quantum secure direct communication (QSDC) world record of 102.2 km (64 miles), smashing the previous mark of 18 km (11 miles), The Eurasian Times reported. Engadget reports: Transmission speeds were extremely slow at 0.54 bits per second, but still good enough for text message and phone call encryption over a distance of 30 km (19 miles), wrote research lead Long Guilu in Nature. The work could eventually lead to hack-proof communication, as any eavesdropping attempt on a quantum line can be instantly detected. QSDC uses the principal of entanglement to secure networks. Quantum physics dictates that entangled particles are linked, so that if you change the property of one by measuring it, the other will instantly change, too -- effectively making hacking impossible. In theory, the particles stay linked even if they're light-years apart, so such systems should work over great distances. The same research team set the previous fiber record, and devised a "novel design of physical system with a new protocol" to achieve the longer distance. They simplified it by eliminating the "complicated active compensation subsystem" used in the previous model. "This enables an ultra-low quantum bit error rate (QBER) and the long-term stability against environmental noises." As a result, the system can withstand much more so-called channel loss that makes it impossible to decode encrypted messages. That in turn allowed them to extend the fiber from 28.3km to the record 102.2 km distance. "The experiment shows that intercity quantum secure direct communication through the fiber is feasible with present-day technology," the team wrote in Nature.

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Arqit says its encryption system can't be broken by quantum computers, but former employees and people outside the company question the relevance of its technology. The Wall Street Journal: A U.K. cybersecurity startup rocketed to a multibillion-dollar valuation when it listed publicly last fall on the promise of making encryption technology that would protect the defense industry, corporations and consumers alike from the prying eyes of next-generation computer systems. Founder and Chief Executive David Williams told investors at the time that his company, Arqit Quantum had an "impressive backlog" of revenue and was ready "for hyperscale growth." But Arqit has given investors an overly optimistic view of its future revenue and the readiness and workability of its signature encryption system, according to former employees and other people familiar with the company, and documents viewed by The Wall Street Journal. While the company says it has a solution to a quantum-computing security challenge that U.S. intelligence last year said "could be devastating to national security systems and the nation," government cybersecurity experts in the U.S. and the U.K. have cast doubt on the utility of Arqit's system. Arqit's stock price reached its highest level to date of $38.06 on Nov. 30 and has since fallen, to $15.06 on April 14, amid a broad pullback of young tech stocks. When the company secured its Nasdaq listing last autumn, its revenue consisted of a handful of government grants and small research contracts, and its signature product was an early-stage prototype unable to encrypt anything in practical use, according to the people. The encryption technology the company hinges on -- a system to protect against next-generation quantum computers -- might never apply beyond niche uses, numerous people inside and outside the company warned, unless there were a major overhaul of internet protocols. Arqit disputed that its encryption system was only a prototype at the company's market debut. "This was a live production software release and not a demonstration or trial," said a company representative. "It was being used by enterprise customers on that day and subsequently for testing and integration purposes, because they need to build Arqit's software into their products."

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