SK Telecom Co., South Korea’s major mobile operator, said on Monday it has developed the country’s first long-distance quantum repeater using quantum cryptography, which is considered the most secure form of communication encryption.

According to the company, it has successfully completed a field test over a trial optical fiber network across three cities in Gyeoggi Province, a distance stretching 112 km.

Quantum cryptography communication relies on the non-replicable property of a quantum, the smallest particle of energy, to create a system that is virtually impossible to hack. Its high level of protection makes it the best security solution in the areas requiring data security, including telecommunications, administration, national defense, finance and medical services, the company said in a statement.

With the advanced quantum repeater, SK Telecom has overcome the distance limitation, which had been viewed as an obstacle to the commercialization of this new technology. Prior transmission distance reached no more than 80 km because of the weak single-photon quantum signals. Now, with multiple repeaters, the distance can be significantly extended. For instance, installing five units of repeaters can cover the transmission distance from Seoul to Busan, which is approximately 460 km.

The telecommunications company has applied its quantum cryptography technologies to the commercial long term evolution (LTE) network in the country’s administrative city of Sejong in 2016 as well as some sections of the network in Daedeok Research Development Complex, in cooperation with the Korea Institute of Science and Technology Information, in May 2017. It plans to partially apply the new technology to commercial networks and gradually expand it to other areas.

With the development of a long-distance quantum repeater, Korea has joined the United States and China in offering the next-generation security technology. The Korean company had spent nearly two years to develop the advanced security solution, according to the company.

By Lim Sung-hyun

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