According to recent reports, Chinese scientists have set a record for the farthest quantum teleportation of a photon. The event took place between a land based laboratory and a satellite orbiting the Earth.
To be clear, the photon did not disappear from the laboratory and then reappear on the satellite, but the information regarding the photon’s state did instantaneously “move” from the lab to the satellite, using a quantum effect known as quantum entanglement. Quantum entanglement is a complicated subject but basically amounts to splitting a photon into two states of quantum probability. The result is not two individual photons, but one photon existing as a probability in two separate locations. When in this state, one half of photon’s polarity can be manipulated in such a way, that the other half reacts identically even if it is separated by the entire the universe. Imagine two stereo’s, one in Canada and the other in Australia, it is like turning the knob on one of the stereos resulting in the other knob turning likewise on its own.
At first glance quantum entanglement seems to defy the speed of light being that there is the possibility of information travelling instantly between two distant locations. This is isn’t the case however, as information regarding the photon’s initial state needs to be transmitted by more traditional methods. Imagine that the stereo knob randomly changes its positions at all times and you can only know its actual position when you decide to transmit the message. Unfortunately, the reader at the other stereo would never know when you took the measurement because his knob would be fluctuating randomly as well.
But at shorter distances, information regarding the photon’s state can be transmitted using a combination of traditional communication and quantum communication. The importance of this, is that messages could easily be quantum encrypted making it very difficult to intercept the transmission.
Could quantum teleportation be used as it is has been popularized in the Star Trek series? Perhaps in theory, but there are very difficult problems to overcome before that can happen. First, although it may be possible to transmit information regarding a particles state, that particle would then need to be recreated at the other end. Not only would you need to rebuild every particle you would need to build it exactly in the same position as the original object. Even if this were possible, it would leave you with two copies of the object that was teleported. In the case of inanimate objects this isn’t a problem, you could simply destroy the original object leaving you with only the teleported object. But what if the object was a human being? Could you destroy the original? The reality of teleportation imagined by Star Trek is that you may indeed face your death each time you are teleported!
Needless to say, it may be best to use quantum teleportation for communication purposes, as apposed to the teleportation of human beings.