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Quantum Teleportation Sends Information 143 Kilometers
SchrodingerZ writes "Scientists from around the world have collaborated to achieve quantum teleportation over 143 kilometers in free space. Quantum information was sent between the Canary Islands of La Palma and Tenerife. Quantum teleportation is not how it is made out in Star Trek, though. Instead of sending an object (in this case a photon) from one location to another; the information of its quantum state is sent, making a photon on the other end look identical to the original. 'Teleportation across 143 kilometres is a crucial milestone in this research, since that is roughly the minimum distance between the ground and orbiting satellites.' It is the hope of the research team that this experiment will lead to commercial use of quantum teleportation to interact with satellites and ground stations. This will increase the efficiency of satellite communication and help with the expansion of quantum internet usage. The full paper on the experiment can be found [note: abstract only, full article paywalled] in the journal Nature."
I was thinking the same thing; if this actually worked reliably, the ~20 minutes to talk to mars would be instantaneous and voyager wouldn't take 20 hours to send shit back home (and both might use substantially less power)
-SaNo
I'll try.
If two events are "time like" then one event occurs before the other *in*all*reference*frames*. i.e. the earlier event could cause the later event. Note that being time like doesn't require the two events to be causally linked but if A causes B then events A and B will be time like
If two events are "space like" then they cannot be causally linked because it is impossible for a signal traveling at the speed of light to get from the first event to the second event in the available time. It also turns out that for space like events different inertial observers don't even agree on which event occurred first. But this causes no problems because events C and D are not causally linked.
If an observer can travel faster than light then the above no longer holds. An observer traveling faster than light will no longer necessarily agree that A happens before B even if A causes B. An appropriate observer can wait for B to happen and then stop A from happening even though it was A that caused B. It is this paradox that leads physicists to assume that faster than light communication is impossible.
The idea of a maximum speed isn't really that crazy anyway. There are only two possible universes, one where there is a maximum speed - which implied time dilation and everything else we see in special relativity - and one where there is no maximum speed - which you get if you take the limit as c approaches infinity in the special relativity equations and turns out to be the newtonian universe. If there is no maximum speed then there is universal time and therefore all events can be uniquely assigned a time and all observers will agree on the ordering.
Tim.
God said, "div D = rho, div B = 0, curl E = -@B/@t, curl H = J + @D/@t," and there was light.
There is some dispute on this. What you say is assumed to be true but has not been proven in any conclusive manner yet and the "why" of it isn't understood. We have a general theory that says the speed of light is the speed limit for everything in the universe and given that we assume this to be true we apply that reasoning to information communicated through quantum entanglement and use the idea of the uncertainty principle to support it. That said it's all assumptions and theories at this point so to better state your response....
No it PROBABLY wouldn't. We don't understand it completely but quantum entanglement is not believed to allow for faster than light communication.
It's mathematically proven that if our current understanding of quantum mechanics is correct that quantum teleportation does not allow faster than light communication. That's not the quite the same thing.
It is the hope of the research team that this experiment will lead to commercial use of quantum teleportation to interact with satellites and ground stations. This will increase the efficiency of satellite communication...
You can't send information via quantum teleportation, so exactly how do they plan to use it in satellite communication?
What you are describing is quantum entanglement, not quantum teleportation. Quantum teleportation needs quantum entanglement to work, but they are two very different things.
With quantum teleportation, the sender absolutely does get to choose the message. The message can be any quantum state. You still can not send messages faster than light of course. To send one qubit, the sender needs to send two classical bits (and use one pair of pre-entangled qubits). You are limited by how fast you can send the two classical bits. If you have a classical message to send, you might as well just send it normally.