Chinese rocket launch
June 16, 2017

Chinese scientists build the first quantum satellite network

A Chinese satellite placed into orbit last summer has successfully used the laws of quantum mechanics to transmit information to Earth using an essentially unbreakable communications channel, according to BBC News and Los Angeles Times reports published Thursday.

The experimental satellite known as Micius was launched from the Gobi desert in August 2016, and it uses delicate optical equipment to beam pairs of entangled photons from orbit to two bases located approximately 1,500 miles (1,200 km) away back atop mountains here on Earth.

The optical equipment onboard the spacecraft distributes the particles of light to encrypt “keys” to secret messages, which can be separated upon receipt at the ground stations, the media outlets said. The experiment, which was detailed in the latest edition of the journal Science, represented the first time that entangled photon pairs have been beamed to Earth from a satellite in orbit.

“This is the first time you have a quantum channel between a satellite and the ground that you can actually use,” Norbert Lütkenhaus, a professor at the University of Waterloo’s Institute for Quantum Computing who was not involved in the research, told the Times. “People have been talking about doing it for many, many years, but these guys actually did it.”

Research could lead to unbreakable communications networks

The team behind this breakthrough was led by Jian-Wei Pan, a researcher at the University of Science and Technology of China, and also involved colleagues from the Shanghai Institute of Technical Physics, the Xinjiang Astronomical Observatory in Urumqi, and elsewhere.

They used entangled photons, pairs of light particles that have no mass and no charge, but which have properties that are and will remain linked, regardless of the distance that separates them, to hide an encryption key using quantum mechanics to create a secret communications channel that essentially could not be hacked, according to BBC News.

At its core, the technique is similar to encryption methods currently used to protect information transmitted by Internet users, the British media outlet explained, but unlike that method, the new quantum-based technique hides the key required to unscramble the encrypted data in photons.

The new study marks the greatest distance over which researchers have been able to separate the entangled photon pairs used to hide the encryption key, while also demonstrating that a quantum-based global communications network is actually possible, the Times said. Their work represents the first measurable proof of a long-theorized-but-never-proven concept, they added.

Lütkenhaus called it “a great engineering triumph,” and Jürgen Volz, a physicist at the Vienna Center for Quantum Science and Technology who was not involved in the work, told the Times that the study proved that it was possible to use a space-based quantum communications network to significantly increase secure transmission distance – a breakthrough “of tremendous importance” in a time “when more and more sensitive information is shared and exchanged via the Web,” he note-----

Image credit: NASA