Physicists Quantum Teleport Photons Over 88 Miles

An international team of researchers has published their paper demonstrating quantum teleportation between two Canary Islands.

Last May, European researchers reported successfully teleporting photos over a distance of 143 km – a little over 88 miles- between two Canary Islands. When I discussed this finding at the time, one of the caveats I had mentioned about this experiment is that it hadn’t yet been peer-reviewed. Well, now it has. The researchers’ findings have been reviewed and published in Nature. The previous record of 97 kilometers by a team of researchers in China was published in Nature earlier this month.

 

Those researchers, who are affiliated with the Austrian Academy of Sciences and other European organizations, used lasers to teleport a photon from one Canary Island to the other. This was a process that required several key innovations, because the most common teleportation solution – using optical fiber – wasn’t an option due to signal degradation.

Xiao-song Ma, one of the scientists involved in the experiment, said in a press release that “The realization of quantum teleportation over a distance of 143 km has been a huge technological challenge.”

That’s putting it mildly. When researchers quantum teleport a photon, they aren’t making it disappear and reappear like on Star Trek. Instead, the information contained in the photon’s quantum state is transmitted from one photon to another through quantum entanglement – without actually travelling the intervening distance.  Unfortunately, this doesn’t mean that information is travelling instantaneously. That’s because the transfer of information occurs when the sender measures the quantum state of their photon. That causes the receiver’s entangled photon to instantly change.

However, in order to understand the information, the receiver has to know what the original measurement was, along with some other instructions. Those instructions are sent via normal communications, which are limited to being no faster than the speed of light.

(If this is making your head hurt, you’re in good company. It makes physicists’ heads hurt, too.)

To all of this complexity, now add weather – over a large body of water, no less. You start to see the problem, because even the most focused lasers can experience a loss of signal when it passes through water, water vapor, etc. And right now, quantum teleportation is an extremely delicate process. Which makes both the Chinese and European researchers’ work – which use different methods – all the more impressive. The European experiment took place over the ocean, and the Chinese experiment crossed a lake.

While quantum teleportation doesn’t lead to instantaneous communication, what it does lead to is incredibly secure communications. That’s because no matter what instructions the sender sends over normal communications channels, those instructions are completely useless without the receiver’s entangled photon. And the sender doesn’t have to know the location of the receiver’s entangled photon. It could be anywhere – there’s no way to track it.

Of course, there’s still a long way to go – decades, perhaps – before this produces any kind of practical communications device. These researchers, however, are eager to move on to the next step – quantum teleportation between the Earth’s surface and a satellite.

“Our experiment shows how mature ‘quantum technologies’ are today, and how useful they can be for practical applications,” said physicist Anton Zeilinger in a press release. “The next step is satellite-based quantum teleportation, which should enable quantum communication on a global scale. We have now taken a major step in this direction and will use our know-how in an international cooperation, which involves our colleagues at the Chinese Academy of Sciences. The goal is to launch a ‘quantum satellite mission’.”

If that mission is successful, then we might start seeing the backbone of a satellite-based, secure, quantum Internet. The applications could be quite fascinating.

(Image Credit: IQOQI/Vienna)

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Alex Knapp, Forbes Staff

Physicists Quantum Teleport Photons Over 88 Miles