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China Launches World's First Quantum Satellite
Aug 27, 2016

Why in news:

Quantum Experiments at Space Scale (QUESS), nicknamed Micius after the philosopher, lifted off from Jiuquan Satellite Launch Center at 1:40 AM local time (late yesterday in the U.S.) and is currently maneuvering itself into a sun-synchronous orbit at 500 km.

What is this all about:

  • It is designed to carry out its mission over the next two years, the QUESS satellite (nicknamed "Micius" in honor of a Chinese philosopher and scientist who lived in the fifth century BCE and is claimed to be one of the very first to conduct optical experiments) will help Chinese scientists run experiments on quantum key distribution between the orbiter and Earth stations, as well as test the ability to maintain secure quantum communications between Beijing and Urumqi – the capital of the Xinjiang Uyghu region in Northwest China.
  • It  isan experiment in the deployment of quantum cryptography — specifically, a prototype that will test whether it’s possible to perform this delicate science from space.

Equipment on board:

Inside QUESS is a crystal that can be stimulated into producing two photons that are “entangled” at a subatomic, quantum level. Entangled photons have certain aspects — polarization, for example — that are the same for both regardless of distance — in fact, the satellite will test that at 1,200 km, which will set a new record. The how and the why are beyond our pay grade here, so just take entanglement as a given. And let’s not even get into the faster-than-light communication argument here.


What hurdle of quantum encryption does Quess try to solve:

  • The trouble with this tech is that photons are rather finicky things, and tend to be bounced, absorbed, and otherwise interfered with when traveling through fibers, air, and so on. QUESS will test whether sending them through space is easier, and whether one of a pair of entangled photons can be successfully sent to the surface while the other remains aboard the satellite.
  • If this proves possible, the satellite will attempt quantum key distribution via these entangled photons. When measured, a photon will show its observers a random polarization state — but critically, entanglement means the other photon will always show the same random state. These correlated polarizations can be the basis of a cryptographic key known only to the observers. (Note: the explanation that was here before was incorrect and has been changed.)

Significance of it:

Quantum communication boasts ultra-high security as a quantum photon can neither be separated nor duplicated. It is hence impossible to wiretap, intercept or crack the information transmitted through it. Quantum communications technology is nearly impossible to hack because any interference to transmission of information destroys it.

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