A

lbert Einstein was never happy with the more

bizarre predictions of the quantum theory that

he had pioneered. In particular he was worried

about what he called “spooky action at a

distance” – the prediction that a measurement

made at a remote location, no matter how distant, could instan-

taneously change the results of a local measurement. He realised

this quantum entanglement violated the concept of a deter-

ministic universe having an independent reality in which the

speed of light limited the propagation of all physical effects

through space.

Nevertheless, following the work of Irish physicist John Bell,

Einstein’s spooky action at a distance has been demonstrated

and confirmed by increasingly rigorous experiments up to

distances of hundreds of kilometres. With the launch of the

Chinese earth satellite Micius in August last year into a Sun-

synchronous low-Earth orbit 500 km high, the bizarre prop-

erty of quantum-entangled pairs of light photons is now being

tested in space as a means of implementing secret worldwide

communication.

Micius represents a major advance in the field of quantum

cryptography, aiming to extend the secure distribution of private

quantum keys to global distances for the first time. It is the

culmination of several decades of international research,

including early Australian work on the feasibility of quantum

cryptography with LEO satellites.

Quantum Experiments at Space Scale

The Miciussatellite is named after the 5th century BC Chinese

philosopher scientist Mozi who, among other things, is said to

have invented the pinhole camera. Miciusis to be the first of a

series of satellite experiments aimed at demonstrating and

implementing an uncrackable international communication

network, with absolute security guaranteed and protected by the

fundamental laws of quantum physics.

The Quantum Experiments at Space Scale (QUESS) project

also aims to investigate quantum entanglement in space in

order to test the fundamentals of quantum mechanics on a

global distance scale. Following 4 months of testing the satel-

lite and its associated acquisition and tracking technology,

handover took place on 18 January 2017, and planned exper-

iments have reportedly commenced.

22 ||MAY/JUNE 2017

Quantum

Satellite

Micius

Challenges

Einstein

PAUL EDWARDS

Quantum cryptography experiments onboard a new Chinese Earth satellite foreshadow secret

communications on a global scale with security guaranteed by the laws of physics.