Scientists are getting closer to enabling a super-secure, super-fast quantum internet: they are now able to ‘teleport’ high-fidelity quantum information over a total distance of 44 kilometers (27 miles).
Both data fidelity and transmission distance are critical when it comes to building a real, working quantum internet, and making progress in any of these areas is cause to celebrate for those building our next-generation communications network.
In this case, the team achieved a confidence level (data accuracy) of more than 90 percent with its quantum information, as well as sending it over extensive fiber optic networks, similar to those that form the backbone of our existing Internet.
“We are thrilled with these results,” said physicist Panagiotis Spentzouris, of the California Institute of Technology’s (Caltech) Fermilab Particle Physics and Accelerator Laboratory.
“This is a significant achievement towards building a technology that will redefine the way we conduct global communications.”
Quantum internet technology uses qubits; unmeasured particles that float in a mix of possible states, such as spinning dice that have yet to settle.
Introduced qubits have ‘entwined’ their identities in ways that become apparent once they are finally measured. Imagine these entwined qubits as a pair of dice – although they can all land on any number, they are both guaranteed to add up to seven no matter how far apart they are. Data in one location instantly reflects data in another.
By cleverly intertwining three qubits, it is possible to force the state of one particle to take over another’s ‘die roll’ through their intertwined partner. In quantum land, this is as good as turning one particle into another and teleporting its identity over a distance in an instant.
However, the entanglement has yet to be identified at first and then maintained while the qubits are sent to their final destination via optical fibers (or satellites).
However, the unstable, delicate nature of quantum information makes it difficult to emit entangled photons without interference over long distances. Longer optical fibers simply mean more chance for noise to disturb the entangled states.
In total, the fiber lengths used to channel each cubit have been added to 44 kilometers, setting a new limit on how far we can transmit entangled qubits and still use them successfully to teleport quantum information.
Never before has it been shown to work with such accuracy over such a long distance, and it brings a quantum network the size of a city closer to reality – even if there is still years of work to do to make that happen.
“With this demonstration, we begin to lay the foundation for the construction of a metropolitan quantum network in the Chicago area,” said Spentzouris.
Quantum entanglement and data teleportation is a complex science, and even the experts don’t fully understand how it can ultimately be used in a quantum network. However, every proof of concept like this that we get brings us a little closer to realizing such a network.
In addition to promising massive boosts in speed and computing power, a quantum internet would be ultra-secure – any hacking attempt would be as good as destroying the chosen slot. At least for now, scientists think that quantum internet networks will act as specialist extensions of the classic internet, rather than as a complete replacement.
Researchers are tackling quantum internet problems from all different angles, which is why you see different distances mentioned in studies – they don’t all measure the same technology, with the same equipment, to test the same standards.
What makes this study special is the accuracy and distance of the quantum entanglement teleportation, as well as the ‘ready-to-use’ equipment used – theoretically it should be relatively easy to scale up this technology with the hardware we already have. .
“We are very proud to have reached this milestone in sustainable, high-performing and scalable quantum teleportation systems,” said Caltech physicist Maria Spiropulu.
“Results will be further improved with system upgrades expected to be completed in the second quarter of 2021.”
The research is published in Such as PRX.