Physicists in China have revealed the details on their ground-breaking experiment to achieve ‘ultra-long-distance quantum teleportation,’ which could pave the way for a global quantum internet.
In a major breakthrough, the team established the first ground-to-satellite quantum network, which allowed them to transmit a photon from an entangled pair up to 870 miles (1,400 kilometers).
Entangled photons theoretically maintain their link across any distance, and have potential to revolutionize secure communications – but, scientists have previously only managed to maintain the bond for about 62 miles (100 km).
WHAT IS QUANTUM ENTANGLEMENT?
In quantum physics, entangled particles remain connected so that actions performed by one affects the behaviour of the other even if they are separated by huge distances.
This means if you measure, ‘up’ for the spin of one photon from an entangled pair, the spin of the other, measured an instant later, will be ‘down’ – even if the two are on opposite sides of the world.
Entanglement takes place when a part of particles interact physically. For instance, a laser beam fired through a certain type of crystal can cause individual light particles to be split into pairs of entangled photons.
The theory that so riled Einstein is also referred to as ‘spooky action at a distance’. Einstein wasn’t happy with theory, because it suggested that information could travel faster than light.
The experiments relied on the ‘quantum satellite’ Micius, which launched to a Sun-synchronous orbit last year from the Jiuquan Satellite Launch Centre.
As the satellite moves through its orbit, its distance from the Tibetan ground station varies from 500 km to 1400 km (310.7 – 869.9 miles).
‘In our experiment, the quantum state to be teleported is the polarization of a single photon,’ the researchers explain in the paper, published to arXiv.
‘Such a single qubit is generated from an observatory ground station in Ngari, and aimed to be teleported to the Micius satellite that has been launched from China on 16th August 2016 to an altitude of ~500 km.’
This setup is what’s known as an uplink configuration, according to the researchers.
The 1,300 pound craft satellite is equipped with a laser beam, which the scientists subjected to a beam splitter.
This gave the beam two distinct polarized states.
In the up-link approach, the transmitter is located at the ground station, while the satellite acts as the receiver.