One year ago Hacked covered the race between the US and China to develop “military super-powers” by harnessing quantum science, and noted that Chinese scientists were developing quantum communication satellites that support unbreakable encryption. A few weeks ago, China launched its first quantum satellite.
On August 16, China launched the world’s first satellite dedicated to testing the fundamentals of quantum communication in space. Dubbed QUESS (Quantum Experiments at Space Scale), the satellite will demonstrate secure communication based on quantum entanglement over unprecedented distances. The QUESS project is led by the Chinese Academy of Sciences (CAS), with the participation of the Institute for Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences.
Unbreakable Quantum Encryption, and ‘Teleportation’
Physicists speak of quantum entanglement when two remote particles share a unique quantum state and exhibit correlated properties. For example, the spins of the two particles could always be in opposite directions. Experimental evidence confirms that entangled correlations are still observed when there is not enough time for light to travel from the first particle to the second, which means that entanglement isn’t limited by the speed of light.
The “spooky action at a distance” found in quantum entanglement has excited the imagination of physicist for decades, as a hypothetical means to achieve faster-than-light communication. Unfortunately, it appears that due to the fundamental randomness of the quantum world, it’s impossible to use using entanglement to send messages.
But the same randomness permits securely sharing keys for one-time pad (OTP) cryptography. OTP encryption is mathematically guaranteed to be unbreakable, but only if the keys are not compromised. Therefore, secure key transmission and storage is the main challenge for ultra-secure OTP cryptography.
That’s where quantum weirdness comes into play: quantum entanglement can be used to establish a shared key in such a way as to permit detecting any attempt to eavesdrop on the key. Therefore, quantum encryption offers complete, invulnerable security based on the laws of fundamental physics.
Quantum computing, a complementary quantum technology, first proposed by Nobel laureate Richard P. Feynman in 1982 (see also Feynman’s Lectures on Computation), could in the future permit cracking all traditional encryption schemes with sophisticated algorithms and superior computing power. But quantum encryption is invulnerable to quantum computing attacks.
The QUESS project will include experiments to “teleport” quantum states of photons, reconstructing them in a new location. “We will beam one photon from an entangled pair created at a ground station in Ali, Tibet, to the satellite,” said Pan. “The quantum state of a third photon in Ali can then be teleported to the particle in space, using the entangled photon in Ali as a conduit.”
Quantum teleportation in space could eventually permit to combine photons from satellites to create a huge distributed telescope with enormous resolution. “You could not just see planets,” said NASA scientist Paul Kwiat, “but in principle read licence plates on Jupiter’s moons.”
After the first QUESS pilot, China plans to launch a fleet of similar satellites to create a super-secure communications network. 20 satellites would be required to enable secure communications throughout the world.”If the first satellite goes well, China will definitely launch more,” said Chaoyang Lu, a physicist at the University of Science and Technology of China, as reported by Nature News.
In a recent article, Foreign Affairs noted that, alongside the QUESS satellite, China is developing large-scale, theoretically unbreakable quantum encryption projects, including the world’s longest quantum communications network, and plans to roll out an operational Asia-Europe quantum communications network in the next five years.
“[The QUESS] program is no mere science experiment,” noted a CAS news release in March. “China is already becoming a world leader in quantum communications technology.”
“A satellite that delivers quantum communications will be a cornerstone for translating cutting-edge research into a strategic asset for Chinese power worldwide.”
Quantum communications networks are so expensive that, according to Foreign Affairs, they could have a “recentralizing effect,” enabling states to recover the ground that they have lost to decentralizing digital technologies.
The very tangible promise and peril of the upcoming quantum technologies may arrive sooner than we think, concludes the Foreign Affairs article. Policy makers and military planners in the West should bear in mind that China is striving to achieve quantum supremacy.
Pictures from Chinese Academy of Sciences and China Daily / Reuters.