- Scientists in China used 'quantum satellite' to send entangled photons 1,200 km
- The satellite produces entangled photon pairs which form an encryption key
- These photons will theoretically remain linked over great distances
- This means that any attempts to listen in will be detected on the other side.
In a major breakthrough for quantum teleportation, scientists in China have successfully transmitted entangled photons farther than ever before, achieving a distance of more than 1,200 km (745 miles) between suborbital space and Earth.
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 100 km (62 miles).
Using the ‘quantum satellite’ Micius, the scientists were able to communicate with three ground stations in China, each more than 1,000 km (621 miles) apart.
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 is illustrated in the artist's impression above.
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.
One of these beams was then used to transmit entangled particles, and the other used to receive the photons.
Pairs of entangled photons fired to ground stations can then form a ‘secret key.’
Theoretically, any attempts to breach this type of communication would be easily detectable.
The satellite launched from Jiuquan Satellite launch Center last year, and the new findings mark a promising step forward in the two-year mission prove successful, which could be followed by a fleet of others if all goes well, according to Nature.
To overcome the complications of long-distance quantum entanglement, scientists often break the line of transmission up, creating smaller segments that can then repeatedly swap, purify, and store the information along the optical fiber, according to the American Association for the Advancement of Science.
The researchers sought to prove that particles can remain entangled across great distances – in this case, nearly 750 miles.
Earlier efforts to demonstrate quantum communication have shown this can be done up to just over 180 miles, and scientists hope that transmitting the photons through space will push this even farther.
When travelling through air and optical fibres, protons get scattered or absorbed, Nature explains, posing challenges to the preservation of the fragile quantum state.
But, photons can travel more smoothly through space.
Achieving quantum communication at such distances would enable the creation of secure worldwide communications networks, allowing two parties to communicate using a shared encryption key.
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.
So, if someone were to attempt to listen in on one end, the disruption would be detectable on the other.
Over the course of the two-year mission, the researchers in China will conduct a Bell test to prove the existence of entanglement at such a great distance.
And, they will attempt to ‘teleport’ quantum states, according to Nature, meaning the quantum state of the photo will be rebuilt in a new location.
Researchers from Canada, Japan, Italy, and Singapore have also revealed plans to conduct quantum experiments in space, including one proposed aboard the International Space Station.
This experiment would attempt to create a reliable and efficient means for teleportation.
By achieving quantum teleportation, the researchers say they could create a telescope with an enormous resolution.
‘You could not just see planets,’ Paul Kwiat, a physicist at the University of Illinois at Urbana–Champaign involved with the Nasa project, ’but in principle read licence plates on Jupiter’s moons.’
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