Encryption is a crucial part of technology, protecting individuals' privacy and finances online. Quantum computing, the next leap forward for the field, needs its own versions of this tech and in a step towards it researchers have now established a new distance record for having a secure quantum communication.

As reported in Nature, researchers were able to share a secret key to be used for encryption and decryption between two receiving stations located 1,120 kilometers (696 miles) apart. The previous record was 404 kilometers (251 miles) and the key was sent over fiber optics. For the new record, the researchers instead employed a satellite.

The Micius satellite is a state-of-the-art quantum receiver and transmitter that has already been exceptional in performing quantum communication. The addition of encryption is an important step forward in the advancement of a future quantum Internet.

In the paper, researchers report that this was achieved with realistic devices, rather than experimental ones. They had two telescopes built in China, in Delingha in Qinghai province, and Nanshan in Xinjiang province, which received the secure key – in the form of an entangled pair of photons – from the satellite. 

Entanglement is a peculiar phenomenon that happens in quantum mechanics. If two particles are entangled, their properties are in a single quantum state, so that once their properties are measured they remain correlated, no matter how far the two individual photons are.

The authors point out that their approach has allowed for the creation of a secure channel to transmit quantum information.

Quantum computers hold the promise to revolutionize many scientific fields from physics to medicine thanks to their incredible computational power. Systems made up of just a few dozens of particles can outperform today’s supercomputers. These machines will allow us to simulate reality like never before and this is why there is so much interest from all scientific sectors in them. 

At the same time, the particles in the quantum states in these computers are incredibly delicate. Entanglement can easily be disrupted and to protect against that quantum computers have to be kept at incredibly low temperatures to work effectively. A quantum computer is yet to be a reality but this, alongside many other technological steps forward, is getting us closer to it.