WHY THIS MATTERS IN BRIEF
- The techniques and devices used to set a new quantum teleportation record will one day allow us to build the robust quantum repeaters that we need to build secure, internet scale quantum networks
Mention teleportation and real sci-fi fans jump out of their sound proofed LED lit dens and jump around for joy waving their hands in the air screaming. At least that’s what I heard they do… so continuing with that theme it’s my pleasure to announce that researchers in the US, from the US National Institute of Standard and Technology (NIST), have successfully teleported information encoded into particles of light over 100 kilometres of optical fibre, smashing the previous distance record of 25 km.
But whoa there sci-fi fans – that doesn’t mean that matter was teleported, that’s still a way away but this type of quantum teleportation could help to greatly improve the security and strength of tomorrows internet connections.
Ah, yes, there we are… the sci-fi fans have all gone back into their dens and now all the cybersecurity experts are jumping for joy. Get back to work guys – the world needs you.
Researchers first proposed quantum teleportation twenty years ago and it relies on a phenomenon known as quantum entanglement, where two particles are inextricably linked, meaning that their states can only be defined by being the opposite of one another – something that Einstein referred to as “spooky action at a distance.”
Because the particles don’t have a defined state until they’re measured this means that as soon as one particle is measured its state will be set, and this will instantly change the state of its other, entangled partner, even when they’re separated by great distances, something that in theory at least produces near light speed communication.
In the past researchers, such as the team in Canada who recently teleported an E-Mail, yes that’s a thing, have managed to teleport information encoded in photons over greater distances through the air, but in this case the teams used traditional fibre optic cable and that, arguably, is more exciting because it could help us create secure quantum internets using existing infrastructure.
Firstly the researchers, who published their work in Optica, created two entangled photons and sent one, known as the “Output Photon,” over 102 km of fibre. Then they determined the state of the other entangled “Helper Photon” by bouncing it off a photon that they already knew the state of.
Here’s a nice diagram to show it in action, feel free to nerd out:
The gallery was not found!
The “state” of the photons in this case was whether they hit the detector early or late, a timeframe that was separated by just a nanosecond.
Once they’d worked out the state of the helper photon, they then knew the state of the output photon, and they used detectors on the other end to confirm their results.
While it’s not a new experimental set up what was different about it is that the detectors the team used, which were made especially by the team to pick up single photons, allowed them to send the information further than ever before.
“Only about 1 percent of photons make it all the way through 100 km of fibre,” said Marty Stevens, one of the researchers involved in the project, “we never could have done this experiment without these new detectors, which can measure this incredibly weak signal.”
Before this, researchers would lose so much quantum data as it travelled through the fibre that they couldn’t send information over more than 25 km – the previous record.
One day the new detector technology that the team built could find its way into devices called quantum repeaters which are like the repeaters we currently use in our networks that receive a signal then retransmit it at a higher level to make our information travel around the whole world. A quantum repeater would do exactly the same thing but using quantum information, and as a result we’d see an explosion in the adoption, size and scale of quantum internet installations which are much more secure than the networks we rely on today.