Researchers at the National Institute of Standards and Technology have just set a new record for quantum teleportation distance. They managed to send information over a distance of 100 kilometers, i.e. how from Krakow to Gliwice or from in front of my desk into space. While it has been possible to transmit the quantum state over slightly longer distances before, laser communications have been used, but the NIST team has set a record for fiber-optic communication. The Americans beat the previous record four times.
Transmission of information via optical fiber involves the loss of some photons along the way, however, unlike direct transmission from the laser to the detector, it does not require both devices to “see” each other. Unfortunately, at a distance of 100 km, the loss of transmitted photons is as high as 99%. Therefore, researchers had to use novel, extremely sensitive detectors.
They used superconducting nanowire single-photon detectors (SPNSD, however strange it sounds). The principle of their operation is as simple as a nanowire. A photon striking a nanowire disrupts its superconductivity, which can easily be read as a change in resistance.
But what does this have to do with quantum teleportation? Well, the phenomenon scientists call quantum teleportation is not as spectacular as the teleportation we know from science fiction movies. It does not imply an immediate transfer of information over any distance. It is just a way to transfer information about the quantum state of one particle with another, whose quantum state is identical (they are “entangled” with each other). In addition, it requires additional information to be sent, which must travel the most traditional route.
So what’s the point of all this fun? The use of entangled particles may be used for data encryption in the future. Quantum entanglement is ideal for transmitting encryption keys – although, as the authors of the experiment admit, there is still a long way to commercialization of the project. Probably much longer than 100 kilometers.
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