Quantum teleportation of macroscopic objects

[hammertime]

I don't use this distinction.
I just say that experiments are done regarding limited-subset-of-full-state, rather than full-state and it seems to be impossible to do any teleportation (or other) experiment operating on the full state.
Photons have well defined full-state: spin, momentum/position, that's all. For atoms that is not so easy.


Reference please!


But I must know what the Hilbert space describing this state is. And teleportation couples only subset of the full-state Hilbert space dimensions.

But it's still possible to teleport the full state - in other words, all the information that describes it - right? It's hard, sure, but doable.

 

[hammertime]

Hammertime, I guess for atoms and "macroscopic" objects like molecules yes, but for a big macroscopic object like a key we are very very far. It seems that for increasing complexity of the object the number of resources used scales exponentially. Even if there is a way, maybe it is too costly.

How do you know it scales exponentially. Can you show me the math?

 

[Drakkith]

Is there a difference between "teleporting" the state of an object and simply transmitting the information about the state of the object?

 

[Ryan_m_b]

Scanning? Teleportation? Nanobots? This is sort of going Star Trek here. Most of this makes little scientific sense. Can you bring it back to a specific question about something which is not born from fiction? Thanks.

I don't see what's so outlandish about this. Can you explain? I've made a few suggestions. Could you please tell me what's wrong with them?

Remember, things like the internet, space travel, and supersonic flight were once science fiction, too.

And alchemy was once considered a science. The fact that something we have no was not envisioned in the past has no bearing on whether or not things now will be envisioned in the future. DrChinese's point is that what you've said doesn't make sense in terms of science. What do you mean by scan (provide specific references from establishes science)? What do you mean by teleportation (provide specific references from establishes science)? What do you mean by nanobots (provide specific references from establishes science)?

On the latter I already responded to you that there was no reality in this. What you are doing here on this thread it seems is asking if your science fiction wish list could come true, ignoring lot's of legitimate opposition to it (like the definitions used for "teleport") and grasping that anything that seems like it supports your dream.

 

[hammertime]

And alchemy was once considered a science. The fact that something we have no was not envisioned in the past has no bearing on whether or not things now will be envisioned in the future. DrChinese's point is that what you've said doesn't make sense in terms of science. What do you mean by scan (provide specific references from establishes science)? What do you mean by teleportation (provide specific references from establishes science)? What do you mean by nanobots (provide specific references from establishes science)?

On the latter I already responded to you that there was no reality in this. What you are doing here on this thread it seems is asking if your science fiction wish list could come true, ignoring lot's of legitimate opposition to it (like the definitions used for "teleport") and grasping that anything that seems like it supports your dream.

What I mean by "scan" is "determine the position and type of each atom" so that we can build an entangled replica at the destination. I'm also wondering if we'll have to "scan" the object by determining the quantum state of each of its constituent atoms.

By "teleportation", I mean quantum teleportation, which has already been demonstrated on atoms and photons. I mean, if we can do it to a single atom, why not large numbers of them? It's just a matter of technical issues, right?

By "nanobots", I mean small, blood-cell-sized machines that traverse the object to scan from the inside, as opposed to having to scan from the outside, like with an ultra hi-res MRI machine.

And, with all due respect, people once said that flight, the internet, and space travel were a "dream". People once said laptops, cell phones, and cars were a "dream".

 

[Ryan_m_b]

What I mean by "scan" is "determine the position and type of each atom" so that we can build an entangled replica at the destination. I'm also wondering if we'll have to "scan" the object by determining the quantum state of each of its constituent atoms.

By "teleportation", I mean quantum teleportation, which has already been demonstrated on atoms and photons. I mean, if we can do it to a single atom, why not large numbers of them? It's just a matter of technical issues, right?

By "nanobots", I mean small, blood-cell-sized machines that traverse the object to scan from the inside, as opposed to having to scan from the outside, like with an ultra hi-res MRI machine.

And, with all due respect, people once said that flight, the internet, and space travel were a "dream". People once said laptops, cell phones, and cars were a "dream".

Ok now provide evidence that these things are possible and if they can be used in the manner you describe. I'm pretty sure that determining the position/momentum etc of all the atoms in a macroscale object whilst it is alive and moving is impossible.

I already addressed your last fallacy. The fact that in the past there were oppositions to ideas that came about has no bearing on whether or not there is a legitimate opposition to a current proposal.

 

[hammertime]

Ok now provide evidence that these things are possible and if they can be used in the manner you describe. I'm pretty sure that determining the position/momentum etc of all the atoms in a macroscale object whilst it is alive and moving is impossible.

You're right. Doing it while the object is alive is impossible. But there's nothing that makes cryogenically freezing the object impossible. Therefore, in principle, it's possible. So let's assume, for argument's sake, that the technical hurdles have been overcome and the object has been cryogenically frozen.

I already addressed your last fallacy. The fact that in the past there were oppositions to ideas that came about has no bearing on whether or not there is a legitimate opposition to a current proposal.

But it shows a trend.

 

[Ryan_m_b]

You're right. Doing it while the object is alive is impossible. But there's nothing that makes cryogenically freezing the object impossible. Therefore, in principle, it's possible. So let's assume, for argument's sake, that the technical hurdles have been overcome and the object has been cryogenically frozen.

This is not a proper way to address any topic. Many of the problems are unknown and addressing those hurdles will likely change the characteristics of the end product. I have already addressed your cryogenic statements https://www.physicsforums.com/showthread.php?t=519258". I must say it is frustrating to deal with your questions only to have you say "well forget about all that and let's just assume that none of those problems exist".

But it shows a trend.

I don't see what you aren't getting here. The fact that things have been discovered before is not indicative that things will be discovered in the future. You can't tack on the success of one field onto an unrelated field just because you want to, it's illogical and fallacious. Otherwise I could use that argument for anything, watch:

-Antimatter powered underwear that rocket jump you to work will be around in ten years
-After all none of that is technically impossible (it's not like FTL or anything)
-Anyone who says anything negative about the practicalities of it don't bother because I don't care, let's assume none of those impracticalities exist
-Anyone who objects still I would like to remind you that people once invented crossbows

 

[xts]

you teleport whichever state you want. You just need to be able to perform the right kind of measurement for teleportation.
Reference fo cont. variables telp.: http://arxiv.org/abs/0910.2713

Not quite as you say. This experiment utilizes Braunstein-Kimble protocol for teleporting continuous variables (S.L.Braunstein, H.J.Kimble, Teleportation of Continuous Quantum Variables, PRL, 26.Jan.1998, http://authors.library.caltech.edu/3827/1/BRAprl98.pdf)

The accuracy of the protocol is limited to measurement accuracy of position and momentum in teleportation scanner. Teleported state is not an exact copy of the original one (like it is in case of discrete variables) - it is just similar to it with accuracy equal to precision of classical measurement.

Even if we improve our precision, we never may reach "perfect" measurement of a continuous variable. Please note that the amount of classical information to be transmitted are outcomes of our measurements of position and momentum - as the accuracy increases, the amount of information increases accordingly. At the limit of "perfect" measurement reasulting with real number, infinite amount of information has to be transmitted.

 

[xts]

Is there a difference between "teleporting" the state of an object and simply transmitting the information about the state of the object?

For quantum objects you can't know the full information about the state, so it even makes little sense to think about complete information about state.

Quantum Teleportation allows you to restore original state of original object at the cost of destroying the original state, transmitting some "classical" information, and utilizing a pair of entangled particles.

 

[DrChinese]

What I mean by "scan" is "determine the position and type of each atom" so that we can build an entangled replica at the destination. I'm also wondering if we'll have to "scan" the object by determining the quantum state of each of its constituent atoms.

By "teleportation", I mean quantum teleportation, which has already been demonstrated on atoms and photons. I mean, if we can do it to a single atom, why not large numbers of them? It's just a matter of technical issues, right?

By "nanobots", I mean small, blood-cell-sized machines that traverse the object to scan from the inside, as opposed to having to scan from the outside, like with an ultra hi-res MRI machine.

And, with all due respect, people once said that flight, the internet, and space travel were a "dream". People once said laptops, cell phones, and cars were a "dream".

You cannot "scan" an atom to determine its properties. This has never been been done and in fact is impossible, I am sure you are aware of the Heisenberg Uncertainty Principle (HUP).

You can entangle 2 particles in such a way that the state of a third can sometimes be teleported (swapped). However, this has never been done on demand, it is simply something that occurs randomly in a subset of events. The remaining subset has nothing relevant changing and there is no way to tell the difference between the two.

You may know more about nanobot potential than I do, but that will not change either of my comments above.

Further, what you are imagining is that you are somehow building an exact replica of an object. That is not teleportation in my book, but regardless it is not feasible under any set of assumptions given that the HUP is accurate. My point is that what you call "difficult" is, for all intents, impossible.

Your analogy of a "dream" likewise makes no sense, as this implies anything is possible given a little time and technology. Good luck with that! Anyway, I don't recall any substantive articles to the effect that the internet, laptops or cell phones were impossible dreams. Early versions of these were around by 1984.

 

[hammertime]

You cannot "scan" an atom to determine its properties. This has never been been done and in fact is impossible, I am sure you are aware of the Heisenberg Uncertainty Principle (HUP).

You can entangle 2 particles in such a way that the state of a third can sometimes be teleported (swapped). However, this has never been done on demand, it is simply something that occurs randomly in a subset of events. The remaining subset has nothing relevant changing and there is no way to tell the difference between the two.

You may know more about nanobot potential than I do, but that will not change either of my comments above.

Further, what you are imagining is that you are somehow building an exact replica of an object. That is not teleportation in my book, but regardless it is not feasible under any set of assumptions given that the HUP is accurate. My point is that what you call "difficult" is, for all intents, impossible.

Your analogy of a "dream" likewise makes no sense, as this implies anything is possible given a little time and technology. Good luck with that! Anyway, I don't recall any substantive articles to the effect that the internet, laptops or cell phones were impossible dreams. Early versions of these were around by 1984.

Why would the HUP prevent building an exact replica of an object? It merely says that the more accurately we measure a particles position, the less accurately we can measure its momentum. But if we were to put an object at very low temperatures, each atoms momentum is negligible. They're essentially at rest. So what would stop us from determining the position of each atom?

Just think of it as a super hi-res MRI.

 

[Ryan_m_b]

You may know more about nanobot potential than I do, but that will not change either of my comments above.

"Nanobots" are one of those fields of science that have far more fictional publications than real. The idea behind it is the concept of building cell like machines but we're nowhere near even beginning to plan on how to design them. Some simple designs for things have been explored but they are akin to Leonardo da Vinvi's helicopters.

Why would the HUP prevent building an exact replica of an object? It merely says that the more accurately we measure a particles position, the less accurately we can measure its momentum. But if we were to put an object at very low temperatures, each atoms momentum is negligible. They're essentially at rest. So what would stop us from determining the position of each atom?

Just think of it as a super hi-res MRI.

You keep saying these things without offering any substance. Do you even understand what an MRI is? It would not help in these situations. Dr Chinese has accurately pointed out with you that there is no technology to completely map all the characteristics of an atom. Yes you can know the position of an atom but an atom is made of subatomic particles that are under the HUP.

And how do you imagine that an atomic "scan" of a bulk object could occur? I think it's time that you provided references for any proposals you have.

 

[DrChinese]

Why would the HUP prevent building an exact replica of an object? It merely says that the more accurately we measure a particles position, the less accurately we can measure its momentum. But if we were to put an object at very low temperatures, each atoms momentum is negligible. They're essentially at rest. So what would stop us from determining the position of each atom?

Then the HUP would be wrong, wouldn't it? So no, cooling an atom does not change that at all.

Of course, you could simply say that "getting close" when replicating an object is good enough. Who knows? But still, replicating an object atom by atom is not teleportation.

 

[hammertime]

Further, what you are imagining is that you are somehow building an exact replica of an object. That is not teleportation in my book, but regardless it is not feasible under any set of assumptions given that the HUP is accurate. My point is that what you call "difficult" is, for all intents, impossible.

Your analogy of a "dream" likewise makes no sense, as this implies anything is possible given a little time and technology. Good luck with that! Anyway, I don't recall any substantive articles to the effect that the internet, laptops or cell phones were impossible dreams. Early versions of these were around by 1984.

And an early version of macroscopic QT is around now. Right now, we can only teleport the state of one atom. Eventually, it'll be a small group (perhaps a few dozen), then a few hundred, etc.

Az Kurzweil puts it, technology grows exponentially. Even when a certain technology (like 2-dimensional transistor-based microprocessors) hits its physical limits, a new technology tends to take its place. So it stands to reason that we'll eventually be able to QT the state of a macroscopic object, thanks to advances in technology and scientific knowledge, right?

All it takes is one guy with a "Eureka!" moment.

 

[K^2]

Unfortunately, difficulty of teleportation of a system also grows exponentially, so the exponential growth of technology is not useful.

 

[Ryan_m_b]

Az Kurzweil puts it, technology grows exponentially. Even when a certain technology (like 2-dimensional transistor-based microprocessors) hits its physical limits, a new technology tends to take its place. So it stands to reason that we'll eventually be able to QT the state of a macroscopic object, thanks to advances in technology and scientific knowledge, right?

Kurzweil is a crackpot. He's taken Moore's law and applied it to everything with absolutely no evidence (his graphs are completely arbitrary with things like "writing" plotted alongside "agriculture" and "the internet" before being used to support his arguments). In other words he has done little more than http://xkcd.com/605/" . He also makes very weak arguments with little understanding of the real science. For example: he baselessly extrapolates Moore's law until there is a laptop that can match the human brain for power (and he made up that figure with some dodgy reasoning about the eye) and says "this is when AI and mind uploading will appear!". I can't remember who said it but one of his critics pointed out that Kurzweil has greatly confused knowledge growth with comprehension. Yes we have far better equipment and more knowledge but we have little more than a puddle of understanding in an ocean of data. Just look at the human genome project, yes we sequenced our entire genome but it's a decade on and we're still chipping away trying to figure out what it means (and we will be doing that for a very long time). A typical pre-2000 kurzweil statement on the subject would run along the lines of "once we've sequenced our genome we will be able to genetically engineer ourselves for immortality". Also please note that just because you can do more of something doesn't mean it will scale infinitely. Sure you can transfer all the properties of one atom to another but how are you going to do that with atoms burried behind others? And how are you going to have an exact stockpile of atoms at the other end in the exact same configurations?

I don't see why this thread has gone on for so long. If you had just read the first part of the wikipedia entry on the subject you will see that you have confused QT with Star Trek teleportation.

Quantum teleportation, or entanglement-assisted teleportation, is a process by which a qubit (the basic unit of quantum information) can be transmitted exactly (in principle) from one location to another, without the qubit being transmitted through the intervening space. It is useful for quantum information processing, however it does not immediately transmit classical information, and therefore cannot be used for communication at superluminal (faster than light) speed. Quantum teleportation is unrelated to the common term teleportation - it does not transport the system itself, and does not concern rearranging particles to copy the form of an object.

 

[hammertime]

What about non-quantum teleportation? What about the things that you see in Star Trek, where a body is converted to energy and then "beamed" to a destination. What challenges lie in the way of doing that?

 

[BruceW]

Quantum teleportation is fine for photons and atoms, since there are not many parameters needed to define the state.
But for a human there are an incredibly huge number of parameters. So to quantum teleport a human, you would have to couple an incredibly huge number of particle pairs.
Also, in quantum teleportation, the original human would be destroyed (since it is not possible to make an exact replica of a quantum state without affecting the original quantum state).
Also, since a classical communication of the outcome of a Bell state measurement must be done, the quantum teleportation can only be completed at the speed of light or less.

To answer "what if a body was converted to energy and beamed to a destination": Well, the only kind of teleportation that has been done is quantum teleportation. So if you were thinking of inventing non-quantum teleportation, you'd need to come up with some other method. (The only other way I can think of is via some kind of wormhole due to the laws of general relativity).

In any case, either of these methods for teleporting a human are way off in the future (if they are even possible at all).

 

[Ryan_m_b]

What about non-quantum teleportation? What about the things that you see in Star Trek, where a body is converted to energy and then "beamed" to a destination. What challenges lie in the way of doing that?

The challenge that there is no known mechanism by which this is possible. You might as well ask "what barriers exist to magic?" If you convert a human body to energy (and how you would achieve total mass-to-energy is a big question) you now just have a huge explosion to deal with. Put it this way, if I explode a nuclear bomb in one direction towards you, how exactly are you going to absorb the explosion and turn it back into a nuclear bomb?

It also violates some fairy fundamental physics, namely the fictional technology somehow maps (perfectly and without interfering) the properties of every particle of the object being transported. This obviously violates the HUP.

 

[xts]

Of course, we have a 'startrek-like' teleportation!
My bank offers automated money transfer service: I put some notes into ATM (they vanish there), and then the recipient peeks identical notes from other ATM enywhere else in Euro lands. Probably that's not a perfect teleportation (notes are likely to have different serial numbers), but their deep meaning (50.€) remains the same. Probably if ATM would be able to dispense coins, the teleportation would be the same, as startrek one.

 

[Drakkith]

Of course, we have a 'startrek-like' teleportation!
My bank offers automated money transfer service: I put some notes into ATM (they vanish there), and then the recipient peeks identical notes from other ATM enywhere else in Euro lands. Probably that's not a perfect teleportation (notes are likely to have different serial numbers), but their deep meaning (50.€) remains the same. Probably if ATM would be able to dispense coins, the teleportation would be the same, as startrek one.

I hate to break it to you, but that isn't teleportation in the least.

 

[Russellbacica]

Teleportation from one place to another is not possible unless the start and end are connected by wires like a fax because you have to strip the object into electrons then reconstruct it at the other end.

 

[Russellbacica]

Quantum teleportation is fine for photons and atoms, since there are not many parameters needed to define the state.
But for a human there are an incredibly huge number of parameters. So to quantum teleport a human, you would have to couple an incredibly huge number of particle pairs.
Also, in quantum teleportation, the original human would be destroyed (since it is not possible to make an exact replica of a quantum state without affecting the original quantum state).
Also, since a classical communication of the outcome of a Bell state measurement must be done, the quantum teleportation can only be completed at the speed of light or less.

To answer "what if a body was converted to energy and beamed to a destination": Well, the only kind of teleportation that has been done is quantum teleportation. So if you were thinking of inventing non-quantum teleportation, you'd need to come up with some other method. (The only other way I can think of is via some kind of wormhole due to the laws of general relativity).

In any case, either of these methods for teleporting a human are way off in the future (if they are even possible at all).

its possible to travel via worm holes but you can't travel place to place
you can only travel into the multiverse sort of like time travel:)

 

[BruceW]

its possible to travel via worm holes but you can't travel place to place
you can only travel into the multiverse sort of like time travel:)

It sounds like you are saying that whenever you go through a wormhole, you would create a parallel universe (which is common in films). But this has nothing to do with general relativity.

In general relativity, spacetime is curved so that although you can't locally exceed the speed of light, you can get to someplace quicker than a beam of light by using a different path through spacetime than that beam of light (i.e. a wormhole).

It is also theoretically possible to make a wormhole such that you can end up in the same place, but at an earlier time than you set off (which seems to mess with causality, but still it is theoretically possible).

Edit: sorry its off-topic, since its not quantum teleportation

 

[hammertime]

So, as we all know, scientists at CERN recently found that some neutrinos APPEAR to travel a bit faster than the speed of light. If it turns out not to be correct, and that relativity has been violated, would this move us any closer to macroscopic teleportation, either classical or quantum? Would it make technologies like it possible?

 

[Drakkith]

According to current QM, I don't think so. Quantum Teleportation doesn't teleport an object, it teleports the "states" of an object. Teleporting an actual object would probably be called a different effect. (Just my guess though)

 

[BruceW]

So, as we all know, scientists at CERN recently found that some neutrinos APPEAR to travel a bit faster than the speed of light. If it turns out not to be correct, and that relativity has been violated, would this move us any closer to macroscopic teleportation, either classical or quantum? Would it make technologies like it possible?

Its an interesting result. I would bet that actually the neutrinos didn't travel faster than the speed of light, due to some part of the experimental set-up that they didn't take into consideration.

But if they really did travel faster than the speed of light, then its a pretty huge discovery.

 

[hammertime]

But if the recent developments at CERN end up being true (i.e. it turns out that something CAN travel faster than light), then what's to stop us from communicating faster than the speed of light? All this time I've heard that one of the limitations of QT is that information can't be transmitted faster than light. Could this prove that wrong?

Also, if it turns out that the speed-of-light-limit is false, then could that also mean that other barriers to teleportation of macroscopic objects could also prove to be surmountable?

How long before we find violations of the HUP or the second law of thermodynamics? Those are considered fundamental limitations, too, just like the speed of light may have been.

 

[Drakkith]

Hammertime, let's not speculate on something that has yet to be proven, let alone things which blatantly violate the current laws of science.