China launches satellite to conduct quantum experiments

The satellite will be used to test quantum communication between two ground stations hundreds of miles apart.
Written by Stephanie Condon, Senior Writer

China has launched a satellite to conduct quantum experiments, according to Chinese state broadcaster CCTV.

Launched from the Gobi Desert at 1:40 Tuesday Beijing time, the Quantum Science Satellite (QSS, also known as QUESS, for Quantum Experiments at Space Scale) will reportedly be used to test quantum communication, quantum entanglement, and the fundamental laws of quantum mechanics.

Beginning with quantum communication, the satellite will attempt to send entangled photons to two ground stations about 746 miles apart. If successful, it could have major implications for cryptography. As noted by Nature, scientists have so far only demonstrated quantum communication at a range of about 300 kilometers. Quantum communication relies on two users sending random strings of numbers to each other as pulses of photons. It allows for the detection of eavesdroppers, since any third party interference would change the quantum state of the string of photons. However, it becomes more difficult to preserve a photon's quantum state as it travels through fiber optical cables and the air.

Researchers around the world have been experimenting with post-quantum cryptography, readying for the development of quantum computers that could break through encryption methods used today.

Along with quantum communication, QUESS will also be used to test quantum entanglement, the phenomenon in which the state of one particle seems linked to the state of another -- even when the two particles are very far apart.

The Chinese satellite, which was designed to operate for two years, is carrying a quantum key communicator, quantum entanglement emitter, quantum entanglement source, quantum experiment controller, and processor and a laser communicator.

If the tests go well, China will launch more quantum satellites, Chaoyang Lu, a physicist who works with the team behind the Chinese satellite, told Nature. He said it would take about 20 satellites to enable secure communications globally.

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