, reflects the indistinguishability of quantum mechanical particles.”
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### Author:  [@Alessan](https://boards.straightdope.com/u/Alessan)
#### Post date: [July 13, 2017, 12:23pm UTC](https://boards.straightdope.com/t/first-a-photon-next-beam-me-up-scotty/791097/6 "2017-07-13T12:23:36Z")
How fast is the transfer of information via quantum teleportation? Speed of light?
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### Author:  [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)
#### Post date: [July 13, 2017, 3:10pm UTC](https://boards.straightdope.com/t/first-a-photon-next-beam-me-up-scotty/791097/7 "2017-07-13T15:10:57Z")
If that’s what counts as “teleportation”, then lets give proper credit to Alexander Bain: He invented the “Electric Printing Telegraph”(aka fax machine) on May 27th, 1843.
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### Author:  [@Richard\_Parker](https://boards.straightdope.com/u/Richard_Parker)
#### Post date: [July 13, 2017, 3:21pm UTC](https://boards.straightdope.com/t/first-a-photon-next-beam-me-up-scotty/791097/8 "2017-07-13T15:21:36Z")
> [@Alessan](#):
>
> How fast is the transfer of information via quantum teleportation? Speed of light?
I think the whole point is that it’s faster than the speed of light.
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### Author:  [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)
#### Post date: [July 13, 2017, 3:34pm UTC](https://boards.straightdope.com/t/first-a-photon-next-beam-me-up-scotty/791097/9 "2017-07-13T15:34:02Z")
> [@Richard\_Parker](#):
>
> I think the whole point is that it’s faster than the speed of light.
I don’t think I saw that in the linked article.
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### Author:  [@Folly](https://boards.straightdope.com/u/Folly)
#### Post date: [July 13, 2017, 3:43pm UTC](https://boards.straightdope.com/t/first-a-photon-next-beam-me-up-scotty/791097/10 "2017-07-13T15:43:02Z")
You still have to send your (one or more) particles to the location you are teleporting at or below the speed of light.
[Here’s a great video](https://www.youtube.com/watch?v=DxQK1WDYI_k) about how it would be unbelievably difficult, but theoretically possible, to teleport a cat. Note, you first have to send a cat’s worth amount of particles to your teleporting location (or at least a bunch of information).
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### Author:  [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)
#### Post date: [July 13, 2017, 5:01pm UTC](https://boards.straightdope.com/t/first-a-photon-next-beam-me-up-scotty/791097/11 "2017-07-13T17:01:16Z")
> [@Alessan](#):
>
> How fast is the transfer of information via quantum teleportation? Speed of light?
The states of the two particles are intrinsically entangled, hence a change in state of one particle will result in the complementary change in the other particle irrespective of the distance between them as measured across Minkowski spacetime. As an observer at Particle A, you would describe the change of Particle B as “instantaneous” insofar as you would see a delay in the change of state of the distant particle consistent with the distance across spacetime, e.g. if the particles were separated by a distance of 1 light-second, you would see a change in the Particle B exactly 1 second following the change of the Particle A. And therein lies the problem with using it for instantaneous communication; because of uncertainty in state, you’d need to know the state of Particle A in order to interpret the state of Particle B, so you need information that is limited by the speed of light. However, “information” is conveyed by the entangled link.
As it happens, the term ‘teleportation’ is entirely appropriate to describe this phenomenon. The etymology of the term derives from the Greek _tele_ (“distant”) and Latin _portare_ (“to carry”), although _contateno_ (“join together”) or _iugo_ (“couple”) might be a better descriptor, since this is not just a transfer of information per se, as in the transmissions of modulation of an electromagnetic carrier wave but an actual cojoining of the two particles as being demonstrating a single unified state. It is unfortunate that this is conflated with the fantastical concept of matter transmission in science fiction which is not remotely plausible in the manner conveyed in _Star Trek_ and other science fiction shows and movies for a vast multitude of reasons which include fundamental problems such as conservation of mass and energy, thermodynamics, et cetera. You cannot ‘teleport’ a physical object, but you could, to a degree of fidelity limited by fundamental quantum uncertainty and the ability of your system to measure and encode the state of all of the components of an object, send information to reproduce the system comprising the object, again restricted by the limitations above.
Regardless, the potential for better understanding quantum entanglement holds both practical value (in terms of utterly secure methods of communication and probabilistic logic versus cryptography using pseudorandom number generation and binary logic) and the potential for better understand the fundamental nature of physics (the mechanics of fundamental interactions not as particles with discrete interactions or collisions but vast interacting fields in the underlying plenum of whatever makes up reality). It will not allow you to dispense with shuttlecraft on your ‘star ship’ to go down and zap rock-creatures with your ‘phaser gun’, but then, you also won’t have to run around wearing spandex onesies either. So, there is a benefit.
Stranger
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### Author:  [@AK84](https://boards.straightdope.com/u/AK84)
#### Post date: [July 13, 2017, 5:55pm UTC](https://boards.straightdope.com/t/first-a-photon-next-beam-me-up-scotty/791097/12 "2017-07-13T17:55:09Z")
> [@Stranger\_On\_A\_Train](#):
>
> The states of the two particles are intrinsically entangled, hence a change in state of one particle will result in the complementary change in the other particle irrespective of the distance between them as measured across Minkowski spacetime. As an observer at Particle A, you would describe the change of Particle B as “instantaneous” insofar as you would see a delay in the change of state of the distant particle consistent with the distance across spacetime, e.g. if the particles were separated by a distance of 1 light-second, you would see a change in the Particle B exactly 1 second following the change of the Particle A. And therein lies the problem with using it for instantaneous communication; because of uncertainty in state, you’d need to know the state of Particle A in order to interpret the state of Particle B, so you need information that is limited by the speed of light. However, “information” is conveyed by the entangled link.
If there are two observers, one at Particle A and one at B, and let’s say separated by 8 light minutes (Earth to Sun). Would observer at B, notice the change at the same time as A? If so, its less a radio and more a one time pad.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [July 13, 2017, 6:03pm UTC](https://boards.straightdope.com/t/first-a-photon-next-beam-me-up-scotty/791097/13 "2017-07-13T18:03:19Z")
Quantum teleportation requires that you already have a classical information channel available, and information travels through that classical channel at c, at the fastest (or possibly slower: The classical information channel could also be, say, a car carrying a CD with some data on it). You can describe the state as changing instantaneously, but that doesn’t matter, because you can’t observe the state without destroying the very entanglement that you’re using.
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### Author:  [@ftg](https://boards.straightdope.com/u/ftg)
#### Post date: [July 13, 2017, 9:06pm UTC](https://boards.straightdope.com/t/first-a-photon-next-beam-me-up-scotty/791097/14 "2017-07-13T21:06:41Z")
Photons aren’t matter. We can send a photon to the Moon and back in 2.5 seconds.
When will be able to send useful matter that distance, with a bounce, in that amount of time?