Scientists are getting closer to enabling a super-secure, super-fast quantum Internet: they could now teleport reliable quantum information over a total distance of 44 kilometers (27 miles).
Both data fidelity and transmission distance are crucial when it comes to building a real, working quantum internet, and making progress in one of these areas is a celebration for those building our next generation communications network.
In this case, the team achieved more than 90 percent fidelity (data accuracy) 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 delighted with these results,” said physicist Panagiotis Spentzouris, of the Fermilab Particle Physics and Accelerator Laboratory, based at the California Institute of Technology (Caltech).
“This is a major achievement on the way to building a technology that will define how we conduct global communications.”
Quantum Internet technology uses kwbits; unmeasured particles that remain suspended in a mixture of possible conditions, such as turning dice that have yet to sink.
Qubits introduced to each other have ‘entangled’ their identities in ways that become obvious once they are finally measured. Imagine that these tangled kwebits are like a dice – although each can land on any number, both are guaranteed to add seven, no matter how far they are. Data in one place immediately reflects data in another place.
By cleverly arranging the entanglement of three qubits, it is possible to force the state of one particle to use the ‘dice roll’ of another via their mutually entangled measure. In quantum land, it is as good as transforming one particle into another, and teleporting its identity within a blink of an eye over a distance.
However, the entanglement has yet to be determined in the beginning, and then maintained, as the qubits are sent to their final destination by means of optical fibers (or satellites).
However, the unstable, delicate nature of quantum information makes it difficult to radiate entangled photons over long distances without interference. Longer optical fiber simply means more chance for noise to interfere with the entangled conditions.
In total, the length of fiber channeled each el was added, 44 kilometers, which sets a new limit on how far we can send entangled qubits and still use them successfully to teleport quantum information.
It has never been shown before that it works with so much accuracy over such a long distance, and it brings a quantum network in the city closer to reality – even though there are still years of work to make it possible.
“With this demonstration, we are beginning to lay the foundations for the establishment of a metropolitan quantum network in Chicago,” says Spentzouris.
Quantum entanglement and data teleportation is a complex science, and not even experts fully understand how it can ultimately be used in a quantum network. However, every proof of this concept we get brings us a little closer to making such a network happen.
Apart from promising a huge increase in speed and computing power, a quantum internet will also be very secure – every hack attempt will be just as good as destroying the lock chosen. For now, scientists think of quantum internet networks as specialist extensions to the classic internet rather than a complete replacement.
Researchers are tackling quantum internet problems from different angles, so you can see different distances mentioned in studies – they do not 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 teleportation of the quantum entanglement, as well as the ‘off the shelf’ equipment used. It should theoretically be relatively easy to scale up this technology using the hardware we already have in place.
“We are very proud to have reached this milestone on sustainable, high-performing and scalable quantum teleportation systems,” said Caltech physicist Maria Spiropulu.
“The results will be further improved with system upgrades we expect to complete by the second quarter of 2021.”
The research was published in PRX Quantum.