B Quantum teleportation from a Curious 10 year Old

[Jacques Marrot]

My brother and I are thinking about the problem that NASA has with sending signals to Mars rovers, and quantum teleportation, is in an instant, therefor we thought you could use that, so we just have a few questions for you. We know this is not possible, since particles can’t teleport for thousands of miles, but just what are those limits? Furthermore, there is only photon teleportation, but this would require electron teleportation, so when might this be possible (I know it is likely a few decades). Thank you so much for your time, and I hope to get a reply soon.

 

[CWatters]

Perhaps have a look at..

https://en.m.wikipedia.org/wiki/Quantum_teleportation

You can in principle do quantum teleportation over long distances (I think current record is about 1200km) but it's not faster than light.

 

[mfb]

There is no distance limit, and you can do this with all particles, not just photons. But to teleport something you always have to send a signal that travels with at most the speed of light - typically this signal is light, then it travels at the speed of light. It doesn't speed up communication at all.

 

[Khashishi]

Quantum teleportation doesn't actually teleport an object. It only transfers the state of an object to another (identical) object.

 

[mingjinghappy]

I think that the information of a quantum state can be teleported with the current technology.
The information of an quantum state can be viewed as infinite complex numbers.
However, an object contains infinitely many atoms. There are infinitely many quantum states.
If we want to teleport a person, all the information should be teleported, such as the information of individual atoms, the information of there connections.
On the other hand, to finish the goal of teleportation, the sender should tell the classical information to the receiver.
Then at least, the people in Mars should have a phone...

 

[Khashishi]

No, an object only contains finitely many atoms.

 

[mingjinghappy]

No, an object only contains finitely many atoms.

Yes, you are right. It is finitely many. But the number may be larger than 10000000000. In the current technology, we can faithfully teleport the 'quantum information (a|0\rangle+b|1\rangle)' of several particles, not the particles themselves. The following expression is wrong: the atoms at one side (A) disappear then appear at another side (B). The correct one is the following: the state of the atoms (A) changes and we can recover the state of the atom by acting some operation on the atom at another side. What operation should we operate? It is dependent on
measurement result at the side (A). That is to say, a 'telephone' should exist between (A) and (B). Then the person at the side (B) can get the information and do the right operation.
I think it is an interesting question philosophically. Suppose that all the atoms of Alice are identical with the atoms of Bob. Are they the same person? If they are the same person, can we develop a technique to copy the state of Alice? Maybe these questions are interesting in fiction.

 

[mfb]

In the current technology, we can faithfully teleport the 'quantum information (a|0\rangle+b|1\rangle)' of several particles, not the particles themselves.

These two things are exactly the same in quantum mechanics. The quantum state is everything that defines a particle or set of particles (apart from the particle types, but they are obviously chosen to be identical).

If they are the same person, can we develop a technique to copy the state of Alice?

No-cloning theorem. You cannot copy the state exactly (in general).

If you are just interested in the philosophical questions you don't need an exact quantum copy. Reproducing the molecules would be sufficient, and these can be copied.

 

[G3N3R4AL RELATIVITY]

Furthermore, there is only photon teleportation.

No, photons are not the only particles that can be “teleported” electrons can. Day that you actually could teleport a electron that far you would already need electron(s) there, and depending on how many there are the Pauli Exclusion Principle could easily get in the way. Although, depending on how many electrons there are, it could be very difficult to detect the single sending particle.