We´ve seen teleportation in hundreds of movies and books. It is the powerful tool that makes you disappear at one place and then occur somewhere else. Teleportation was a matter of sci-fi and fantasy stories for many years, but it seems now, that scientists are really on a track to find a way how to “teleport” particles.
The process is called quantum teleportation and is based on a phenomenon called quantum entanglement. Quantum entanglement is a state in which two objects (nowadays we use particles, for example photons) are linked together even when they are very far away from each other. This link between them is strange and it needs to be created by scientists (for example by dividing two photons from one at the same time and the exact same point in space), scientists call this state “correlation” and the two photons then depend on each other even when they are separated by distance.
In this state of quantum entanglement, if we look at the current state of one of the particles, the second particle immediately turns out to be the in the opposite state. Imagine that you have two coins instead of particles, and you flip them. If the first coin is head, then you know that the second coin is tail. Basically, it means that the measurement on one immediately influences the other, no matter how far they are. Einstein called this “spooky action at a distance” and he completely disagreed with the existence of such phenomenon. However, the truth is that it´s been already proved by experiments, first time with photons in 1998.
This is the basics for quantum teleportation. Scientists realized that they could transmit quantum information of the first photon to another. So, if we measure all the information about the first photon, we can send it to the second photon, which creates the perfect copy with the same information as had the original photon – simply said, the receiving photon becomes the first photon because the first photon is destroyed.
Chinese Scientists set new record in quantum teleportation in 2017. They sent a packet of information about the quantum state of a photon (polarization) to a satellite called Micius that is up to 1400 kilometers above the Earth´s surface. It is the longest distance the information has been sent to far, and it was also the first time the information was sent from Earth to space.
Such a distance is a great success because this process has a limitation. Entanglement can be easily destroyed when the photons interact with other matter. Theoretically the entanglement should have no distance limitation, but practically the scientists have trouble overcoming 100 km. This is maybe one of the reasons, why the Chinese study hasn´t been peer-reviewed yet.
Second problem is that for real teleportation, we need to transfer all the information about the first photon (as was already mentioned). Only if we know all the states of the original photon, and we manage to transmit all of them, we can say that this was a real quantum teleportation. In the case of Chinese experiment was transmitted only one information (polarization), but it is still a great success because it is very difficult to transfer more information and it requires to control more photons than we can do now.
To be honest, it is hard to imagine that we could ever transmit human, but the quantum teleportation will allow us to develop new superfast quantum computers and to develop safe quantum-communication.