China launched Quess satellite
China has launched the world’s first
quantum satellite- Quantum Experiments at Space Scale, or QUESS. It is an effort to establish communications that cannot be hacked.
Details:
- In its two-year mission, QUESS is designed to establish ‘hack-proof’ quantum communications by transmitting uncrackable keys from space to the ground.
- The satellite will be put into Earth orbit around 500 km above ground.
- The craft’s main instrument is a “Sagnac” interferometer that is used to generate two entangled infrared photons by shining an ultraviolet laser on a non-linear optical crystal.
- The main goals of QUESS will be to demonstrate quantum key distribution (QKD) between the satellite and two stations on the ground – the Nanshan 25 m telescope at the Xinjiang Astronomical Observatory in western China and the Xinglong Observatory in Yanshan, around 200 km south of Beijing.
How does it work?
The satellite will create pairs of so-called entangled photons –
tiny sub-atomic particles of light whose properties are dependent on each other
– beaming one half of each pair down to base stations in China and Austria.
- This special kind of laser has several curious properties, one of which is known as “the observer effect” – its quantum state cannot be observed without changing it.
- So, if the satellite were to encode an encryption key in that quantum state, any interception would be obvious. It would also change the key, making it useless.
- If it works, it will solve the central problem of encrypted communications – how to distribute keys without interception – promising hack-proof communications. The encrypted message itself can be transmitted normally after the key exchange.
Background:
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.
