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hammertime
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Scientists have reportedly been able to transport atoms and molecules as much as 1800 feet. Could the same be done for humans, or would the Heisenberg Uncertainty Principle ultimately make it impossible?
hammertime said:Scientists have reportedly been able to transport atoms and molecules as much as 1800 feet. Could the same be done for humans, or would the Heisenberg Uncertainty Principle ultimately make it impossible?
Glen Bartusch said:Technically, the Physicists involved in the research you indicated did not "teleport atoms" ex-number of feet. Rather, the physicists were proving the GHZ hypothesis, which is a hypothesis to violate Bell's Inequalities. In other words, the experiment demonstrated a phonomena called entanglement. There was no sending of atoms "from here to there using a teleportation device".
The uncertainty principle states that the quantity of one non-commuting observable becomes less known when the quantity of the other observable becomes more known. Thus, the HUP has nothing to do with 'teleportation'. Note that the HUP applies to quantum systems, only.
I would agree with Glen that teleportation processes have absolutely nothing to do with the uncertainty principle.hammertime said:Well would the HUP make a device like, say, a transporter from Star Trek impossible?
Fightfish said:I would agree with Glen that teleportation processes have absolutely nothing to do with the uncertainty principle.
However, I do not agree that the "teleportation processes" were simply just experiments proving the GHZ hypothesis. There was indeed teleportation of some form (the meaning of this teleportation as that defined by Charles Bennett in his seminal paper). This teleportation obviously does not defy any physical laws; it involves the teleportation of a quantum state (information) across space. Recently, Hotta proposed and studied a scheme for the teleportation of energy as well.
It may help if I briefly describe Bennett's standard teleportation protocol. Using the standard communication terminologies, we have two characters Alice and Bob. Now, Alice has a particle prepared in a certain state unknown to her, and she wishes to communicate that information to Bob, giving him a replica of that particle state. Trivially Alice can give the particle to Bob directly, but there may be reasons against that. (for instance, if the quantum channel that I am about to describe has already been set up, it is far easier to "teleport" the state)
To establish the quantum channel, Alice prepares another two particles in an EPR singlet state (ie the two particles are entangled), and sends one of the particles to Bob. She then performs a joint measurement on the initial particle and her channel particle, entangling the three particles. The measurement will cause the system to collapse into one of several possible states, and destroy the entanglement. Based on her results, Alice has to communicate classically with Bob such that he can perform the appropriate recovery operations (Pauli rotations) in order to turn the state of his particle into the original one Alice had. As such, the particle is not physically teleported across space; it is the information, the state of the particle that is teleported to another particle.
Refer to: C. H. Bennett, G. Brassard, C. Crépeau, R. Jozsa, A. Peres, W. K. Wootters, Teleporting an Unknown Quantum State via Dual Classical and Einstein-Podolsky-Rosen Channels, Phys. Rev. Lett. 70, 1895-1899 (1993) for more information.
Now, in the quantum realm, particles are indistinguishable. We cannot for instance, tell two free electrons apart. So, in order to "teleport" humans, we need humans to be decomposed into indistinguishable entities loaded with "states" that make us who we are. Then, we will have a quantum channel comprising two such entities and your state is teleported from your originally occupied entity to the one at the destination. Even ignoring decoherence and the fact that you are a classical object, this sounds rather ludicrous to me.
hammertime said:So, long story short, are "Star Trek" style transporters are physically unlikely? Physically impossible?
ZapperZ said:How about this answer: It hasn't been shown convincingly yet (as in experimentally) to be possible.
Will that answer get you to actually spend time trying to understand what is meant by "quantum teleportation"?
Zz.
hammertime said:I actually somewhat understand what quantum teleportation is. I'm more curious as to how physical teleportation (again, a la Star Trek) can be achieved. So is it, at least in theory, possible? Could there be something we don't know about the laws of physics that could allow Scotty to beam us up?
CLB788 said:"Quantum Teleportation" has been experimentally verified for qubit states of photons and atoms. See the following references.
ZapperZ said:You need to read a bit more carefully. The references you quoted, and all the so-called "teleportation" experiments are demonstration of quantum entanglement of the STATES. It isn't a teleportation of the object itself!
CLB788 said:I'm fully aware that it is just teleportation of the "quantum state", not the object itself. That's why I said that teleportation has been verified for "qubit states" of photons and atoms. I debated about adding that clarification to an already long post. However, given that sub-atomic particles of the same type are indistinguishable (i.e. one electron is just like any other electron--the only differences between electrons are the quantum states that they are in), all that matters is that the quantum state is teleported from one particle to the other. Once the state of electron A has been teleported to electron B, electron B looks and behaves exactly like electron A, so it is just as good as having the original electron A at the new location. As has been said before, you are teleporting information about the quantum state of the original object. In effect, Bob creates a copy of the original object, though the copying process destroys the original.
...Also, I'm aware that it was not the entire state vector for the photons that was teleported, only the portion of the state vector describing the spin state (or in some experiments it was the polarization state). So far, only two-dimensional vector states have been teleported, but it is theoretically possible to teleport state vectors of higher dimension.
ZapperZ said:So then, what are you disputing with my posting by citing all this? Isn't this rather highly irrelevant in light of what the OP is now asking for? Did you think ANY of the papers you cited actually showed the teleportation of an object from one location to another? It is the entangled observable that is involved here, not the object!
CLB788 said:We both agree that the object itself is not teleported, it is the quantum state that is teleported. The point is that, for all intents and purposes, a particle at point B in the state [itex]\psi[/itex] is identical to a particle at point A in the state [itex]\psi[/itex]. Furthermore, after the teleportation, the particle at point A is no longer in the state [itex]\psi[/itex]--it has collapsed into one of the eigenstates because it was measured by Alice. If I teleport my computer from Los Angeles to New York, clearly it is not constructed out of the exact same electrons, protons, and neutrons that it was made out of in L.A., but it is still made out of the same number of electrons, protons, and neutrons that are collectively in the same quantum state that my computer was in before it was teleported. So my computer will still have all the same data and programs on it, and it will still run just as well as it did in L.A. There will be absolutely no observable difference between the teleported computer and the original computer. In my view, this means I have succeeded in teleporting my computer. The particular atoms and molecules making up a human are continuously being replaced through the biological processes of cell death, growth, and regeneration--the question of which particular particles in the universe make up a human is metaphysics. What is physically important is the configuration of those particles--the quantum state. So the answer to the original poster's question is yes, you can in theory teleport a human.
CLB788 said:"Quantum Teleportation" has been experimentally verified for qubit states of photons and atoms. See the following references.
Experimental quantum teleportation
D Bouwmeester; J W Pan; K Mattle; M Eibl; H Weinfurter; A Zeilinger
Nature; Dec 11, 1997; vol. 390, pages 575-579
Deterministic quantum teleportation with atoms
M Riebe; H Haffner; C F Roos; W Hansel; et al.
Nature; Jun 17, 2004; vol. 429, pages 734-737
Deterministic quantum teleportation of atomic qubits
M D Barrett; J Chiaverini; T Schaetz; J Britton; et al.
Nature; Jun 17, 2004; vol. 429, pages 737-739
Penrose's book was published in 1989, before Bennett et al. published their paper proposing quantum teleportation in 1993. Before Bennett et al., physicists were unaware of the possibility of "teleporting" a quantum state with "perfect" fidelity. So it turns out that it is theoretically possible to teleport a human, and so far experimenters have actually been able to teleport qubit states of photons and atoms. However, it would be immensely difficult to actually teleport a human, because first we would need to (as described by Fightfish above) create two human-sized blobs of matter that are entangled, and physically transport (the old fashioned way) one of the blobs of matter to the place that we want to teleport the human, all the while maintaining the entanglement of the two blobs of matter. As Fightfish mentioned, humans are essentially classical objects, which indicates that it would be extremely difficult to entangle two human sized objects, and extremely difficult to maintain that entanglement during the physical transport process. The blobs of matter would interact with the environment in such a way that the purity of their quantum state would be destroyed (decoherence) and they would become essentially classical objects again. Without the pair of entangled human-size objects, one at the departure location and one at the destination location, it would be impossible to teleport a human.
Note that teleportation does not allow you to travel faster than the speed of light. Before your teleportation is complete, Alice has to send the results of her measurement to Bob, via a classical communication channel (radio waves or whatever). Once Bob receives the results, he can perform some operations on his entangled blob to recover the human. Also, this teleportation presupposes that one of the entangled blobs has already been physically transported to Bob's location, so, if you factor this into the travel time, then the maximum teleportation speed is half the speed of light. Also note that the teleportation process destroys the original "copy" of the human. This means that you don't really exist anywhere for the time during which the classical message is being sent from Alice to Bob.
Finally, if we suppose that we could overcome the technical difficulties of teleporting a human, we are still left with the following question: If I teleport my body from Earth to Mars, does my mind follow it? Science still has a very poor understanding of the relationship between the mind and body. Some philosophers would say that mind is a different type of substance from body. It's not clear if my mind, with all my memories and my sense of identity, will be intact after teleporting my brain to Mars. Am I still the same person I was before I was teleported?
Jeff Reid said:The movie "Prestige", got the right idea behind "transporters". You make a copy, then optionally destroy the original.
Jeff Reid said:The movie "Prestige", got the right idea behind "transporters". You make a copy, then optionally destroy the original.
No I don't think you get the original back, just an approximate copy. An analogy would be using some type of laser scanning device on a simple, single material object, sending the data to a manufacturing site, that would then use a computerized cutter tool to make an approximate copy.ZapperZ said:The problem here is that you made a copy of WHAT? When you reconstruct that atom, do you think you are getting the ORIGINAL atom back?
hammertime said:So would teleportation of a human using the method you described involve disintegrating, and therefore killing, the human who's being teleported?
hammertime said:Also, in his book 'The Physics of Star Trek', Lawrence Krauss says:
"The operation of quantum teleportation requires very carefully prepared initial quantum states and then a system that is isolated from its environment throughout the process. Nothing could be further from the situation we exist in, however. We are not quantum objects. If we were, the laws of quantum mechanics would not seem so strange. Macroscopic objects like humans are complex configurations of many particles interacting so frequently with each other and their environment that all quantum mechanical correlations and entanglements are quickly destroyed."
What exactly does this mean? Is it true?
hammertime said:Teleporting a human seems near impossible. However, would it be made any easier with advances in technology (singularity, AI, quantum computing, etc.) and energy (fusion)?
Also, regarding the decoherence of the blobs of matter, is this what Krauss was talking about in his book?
hammertime said:So would teleportation of a human using the method you described involve disintegrating, and therefore killing, the human who's being teleported?
CLB788 said:Yes, this teleportation method would destroy the original version of the human. Though, when I say destroy, I don't mean that the human just disappears. The particles making up the human will still be there, but they will be in a state that probably won't look too much like an alive human.
Advances in quantum computing could help the field of quantum teleportation, and vice versa, because quantum computing and quantum teleportation are very closely related fields.
Yeah, the decoherence of the blobs of matter is the same thing that Krauss was talking about in The Physics of Star Trek. The original quantum teleportation proposal by Bennett et al. was a simple process involving an isolated quantum system. If the system is perfectly isolated, we don't need to worry about unwanted interactions between the particles in the system and particles in the surrounding environment. But in the real world there are always unwanted interactions that create "quantum noise" or "decoherence". In other words, the interaction of the system with the environment can mess up the entangled quantum states that are needed to perform the teleportation. This problem becomes more and more difficult to deal with as the system becomes more macroscopic.
hammertime said:So you're saying that the interactions between particles in the system and between the system and the environment cause decoherence. So would this decoherence essentially render the teleportation impossible? Can it be overcome by, say, putting a human in a suit and then putting him in a vacuum?
Can all of these limitations be overcome, however, with sufficiently advanced technology? Michio Kaku says it's possible within a century, I believe. Couldn't, say, a type II civilization do it?
CLB788 said:Yes, the decoherence/quantum noise does make the teleportation of a human extremely difficult. I'm guessing that putting a human in a vacuum does reduce the quantum noise to some degree, but that measure alone would probably not be nearly enough. One thing to keep in mind regarding vacuum is that even the best laboratory vacuums (pressures of around 10-12 torr) still have a particle density of around 35,000 particles per cubic centimeter. So a human in an ultrahigh vacuum still has plenty of interaction with the environment.
threadmark said:Teleporting: hmmm what an interesting topic. Transportation over a distance instantly through space. Although this does not come across to me as a physical possibility, it is still fun to think about.
threadmark said:The definition of teleport is to transport across space and distance instantly. So Don’t correct me correct the Oxford dictionary.
The Heisenberg Uncertainty Principle is a fundamental principle in quantum mechanics that states that it is impossible to know the exact position and momentum of a particle at the same time. This means that the more precisely we know the position of a particle, the less we know about its momentum, and vice versa.
Human teleportation involves breaking down a person's physical body into particles and then reassembling them in a different location. This process would require knowing the exact position and momentum of each particle, which is impossible according to the Heisenberg Uncertainty Principle.
There is currently no known way to overcome the Heisenberg Uncertainty Principle. It is a fundamental principle of quantum mechanics and has been proven through numerous experiments. Therefore, it is unlikely that human teleportation will ever be possible.
Yes, there are many other obstacles to human teleportation, including the immense amount of energy required to break down and reassemble a human body, the ethical concerns surrounding the destruction of one's original body, and the potential for errors or malfunctions during the teleportation process.
While it is impossible to predict the future, it is highly unlikely that human teleportation will ever be possible due to the limitations of the Heisenberg Uncertainty Principle. However, advancements in technology and science may lead to other forms of transportation that are more efficient and faster than traditional methods.