China will complete and put into service the world's longest quantum communication network stretching 2,000km from Beijing to Shanghai by 2016, say scientists leading the project.

The quantum network is considered "unhackable" and will provide the most secure encryption technology to users.

By 2030, the Chinese network would be extended worldwide, Xinhua reported.

China is the first major power to come up with a detailed schedule to put the technology into extensive, large-scale use. The South China Morning Post earlier reported that Beijing would launch the world's first quantum communication satellite in 2016.

Xinhua said the network would be used by the central government, military and critical business institutions like banks.

The ambitious targets were revealed by Professor Pan Jianwei, a quantum physicist with the University of Science and Technology of China and a lead scientist of the national quantum communication project, during an international conference on quantum communication in Hebei yesterday, Xinhua reported.

"China's quantum information science and technology is developing very fast and China leads in some areas in this field," he was quoted as saying. "Any city in China, as long they want to, can start to build the quantum communication network now."

Chen Yuxiang , USTC quantum physicist and chief engineer for the construction of the Beijing-Shanghai link, said the key infrastructure would be completed between the end of the year and next summer.

Then the link would be built and activated, with the inclusion of existing quantum networks in other cities such as Hefei and Jinan .

Edward Snowden's revelations last year that the US was targeting "network backbones", through which huge amounts of data are transmitted, convinced Chinese leaders that developing the next generation of internet infrastructure was a priority.

A quantum communication network is, in theory, unbreakable. Any attempt to intercept the encryption key would alter the physical status of the quantum data, or qubits, and trigger an alert to the communicators.

Though the technology was proposed by IBM scientists as early as the 1980s, quantum communication has been limited to short distances due to the technological difficulty in maintaining the qubit's fragile quantum state, such as spin, over a long distance.

China was in a race with other countries to develop the technology and, thanks to generous funding, scientists achieved numerous significant breakthroughs in recent years. Pan's team conducted the world's first experiment on quantum key distribution from a satellite last year.

Governments in Europe, Japan and Canada are about to launch their own quantum communication satellite projects and a private company in the US has been seeking funding from the federal government with a proposal for a 10,000km network linking major cities.

The Beijing-Shanghai project was launched last year. Though the government has not revealed its budget, mainland scientists told state media that the construction cost would be 100 million yuan (HK$126 million) for every 10,000 users.

South China Morning Post, Stephen Chen, 2014-11-04, http://www.scmp.com/news/china/article/1631479/china-launch-hack-proof-quantum-communication-network-2016