On Thursday, a team of Chinese scientists released findings from a breakthrough study that makes China the indisputable leader in the field of quantum communication, an achievement that could be of immense strategic importance.
The study, led by Pan Jianwei and published in Science magazine, successfully demonstrated the ability to distribute entangled photons across unprecedented distances, from space to earth, opening the door for the practical application of cutting-edge, ultra-secure communication.
In the wake of China’s milestone, some in the scientific community outside of China are eager for their own governments to play catch up in the quantum space race.
Anton Zeilinger, a physicist at the Austrian Academy of Sciences, has pushed his government to launch a quantum satellite of its own, telling Science that this test “shows that China is making the right decisions, […] I’m personally convinced that the internet of the future will be based on these quantum principles.”
Until now, entanglement distribution has only been achieved across a physical separation of less than 100 km, limited by the photon loss in channels such as optical fibers, which increases exponentially with the length of the channel. This test, set in motion when China launched a specialized quantum satellite dubbed Micius last year, was able to distribute the entanglement photons across a distance of more than 1,200 km.
The space-based approach offers a key advantage in achieving the longer distance transmission as most of the photons’ path is through the vacuum of space, with turbulence largely occurring only within the lower 10 km of the atmosphere. In order to exploit this advantage, the scientists used a laser-based entangled-photon source especially resistant to disturbance.
This achievement is a huge step towards the practical application on a global scale of a theoretically unhackable encryption method called quantum key distribution.
Encryption methods used today are nearly, but not completely, impossible to hack, but with more advanced computing power the forms of encoding that protect information sent online will become more and more vulnerable. Quantum key distribution, however, is unique in that any measurement of the transmission by an eavesdropper disturbs the transmission, thereby alerting the parties sending information.
It will take a while to go from what this team of scientists accomplished to the widespread practical application, but they are moving at a fast pace in the right direction. According to Pan, the lead physicist on the study, China’s National Space Science Center will launch additional satellites with stronger and cleaner laser beams detectable even when the sun is shining.
“In the next five years we plan to launch some really practical quantum satellites,” Pan said, speaking to Science.