But will we ever be able to teleport people?

There are some 10^29 matter particles comprising a human person, each of which has position and momentum degrees of freedom in addition to spin. In principle, we might also need to teleport the photons, gluons and other energy particles comprising a person. Teleporting all that is going to be significantly harder than a few thousand spins. It is probably a good guess that teleportation of humans will never be possible.

Are we at least sure that it is possible to teleport humans in principle?

While most scientists expect that ten, hundreds and maybe even thousands of spins will be teleported in practice some day, the teleportation of a human being, even in principle, is actually still a controversial subject.

I would roughly divide people into three schools of thought.

The first group of physicists would argue that there is a soul, consciousness or spirit that permeates the human body that cannot be described by science. Unfortunately, in this view by definition we are prevented from using science to determine if teleportation is feasible.

A second group of physicists would disagree with human teleportation because of something known as the measurement problem. Roughly speaking, any object that is capable of performing quantum measurements cannot itself be a quantum object, and therefore cannot be teleported using quantum teleportation. In this view, small numbers of particles are quantum but at some point when you combine enough particles you end up with a classical or "observer" object, which cannot be described by the laws of quantum mechanics.

In principle, such a belief will have experimental consequences, as we should be able to determine at what point do objects stop being quantum mechanical. At the moment there is neither any experimental evidence for such observer objects nor even a consistent theory that could describe them. On the other hand, it is also true that presently it is very hard to experimentally study large quantum systems, and so it is quite possible that something interesting will happen when a large enough system is examined.

The third school of though (which I am partial to) would say that all objects big and small are quantum mechanical, and therefore in principle can be teleported. What happened with the measurement problem? I would argue that measurements never actually occur. What happens is that the observer becomes entangled with the system he is measuring, and this appears to the observer as if a measurement was performed. The mathematics for this process works out quite nicely, but it does leave the nagging question of why does it feel like we are constantly measuring the world?

Of course, the final answer to whether teleportation of people is possible even in principle must wait for the formulation of a complete theory of physics, one which unifies relativity with quantum mechanics.

In the meantime, one can ask if there any applications for teleporting thousands of spins?

The answer is probably yes. In the future it is likely that quantum computers (i.e., computers capable of processing quantum information) will be built and may even be as ubiquitous as classical computers are today. These computers will need to exchange quantum information. One way these exchanges of information can occur is via a quantum phone, that is, a device capable of sending and received quantum messages. But when such phones are not available, the alternative is to do teleportation using a regular phone. So don't be surprised if some day in the next 100 years you see a quantum teleportation device for sale in your local computer store.uction to Quantum Teleportation