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Quantum teleportation-is it real?

  1. May 7, 2010 #1
    I am writing this post to cover my doubts on this amazing piece of technological advancement;Quantum teleportation.

    Basically, Quantum teleportation is a hypothesized form of travel in which matter is converted to electric data which is then reconverted back to matter. Now, from what i have read, the theory behind this is incredibly hard to understand. I would appreciate it if someone would help me understand it.Currently, this technology is still in the developmental stages.It would be another couple of centuries before it can actually be put into commercial use.

    My doubts are:-

    1. Is this really possible??

    2.What is the maximum possible speed that can be achieved???

    3.Can there be hazardous situations where the atoms are rearranged in the wrong way???

    4.What are the drawbacks(if any)???

    5.What is holding this technology back???
     
  2. jcsd
  3. May 7, 2010 #2
    For 1 atom - yes
    For complicated systems - no for 2 main reasons:
    1. when you start to measure positions of atoms in complicated systems you heat it. Delicate systems (biological) die.
    2. you can not even start measuring the positions of atoms INSIDE the brain without destroying it's surface.
     
  4. May 7, 2010 #3
    Quantum teleportation is real, yes.


    Transmission speed? c, same as any other sort of signal. (No, quantum entanglement can not be used to transmit real information faster than c.)


    Given that it would be utterly impractical to teleport the state of systems of more than a handful of particles...there's not much hazard such a situation could cause.


    No practical use is a major one.


    The laws of physics.

    Quantum teleportation is a class of physics experiments in which the quantum states of one system of particles are copied to another system of particles. It is only of use for testing theory and equipment. It can not and never will be used for teleportation of macroscopic objects as you see on Star Trek. It's not a matter of sufficiently advanced technology...the fundamental problem is that the complexity of the interactions between particles in a system increases explosively with the number of particles...each particle added can interact with all the other particles in the system in multiple ways, and even a small object is made of trillions of trillions of atoms, each with dozens of electrons, protons, and neutrons. The human body? About 2.3e28 protons, the same number of electrons, and 1.8e28 neutrons. One billion counters running at 10 GHz would take 73 years to count 2.3e28 pulses...and that's just counting the same number of pulses as the human body has electrons, not doing any real processing or any sort of scanning, and certainly not measuring all the quantum state of a human body.

    There's just no way to read the state of every single particle in a human body, any method that could would require applying absurdly impractical amounts of energy (think "Earth-shattering kaboom"), and that's only a small fraction of the problem...you've then got to reassemble a human at the destination. Even teleporting small, simple objects will be utterly impractical. The only possible practical use for quantum teleportation I see outside of research would be things like molecular circuitry assembly...apply the same techniques used in the "teleportation" experiments to copy patterns into atoms embedded in a substrate, inducing them to form desired structures.
     
  5. May 10, 2010 #4
    The main "issue" is that quantum teleportation does not teleport matter, but rather information.

    A quantum bit in an unknown state (read superposition state) cannot be perfectly copied to another qubit (confer the no cloning theorem). There is however still a procedure to transfer all information from one qubit to another, under the condition that the information in the first qubit is destroyed. This process is called quantum teleportation, and it effectively teleports quantum information from one place to another (at a speed of at most c), not matter, as you need all needed matter already setup at the new location.

    This is why it has no use for macroscopic objects (such as humans), since most (if not all) parts of us are classical, there would be no benefit at all to use quantum teleportation for us.
     
  6. May 20, 2010 #5
    I was reading this article today and started thinking about it, figured I would search it on PF to find out more.

    http://arstechnica.com/science/news...ion-achieved-over-ten-miles-of-free-space.ars


    "Transmission speed? c, same as any other sort of signal. (No, quantum entanglement can not be used to transmit real information faster than c.)"

    I was wondering about teleporting digital information for communication purposes. With our current quantum teleportation could it be possible to transmit digital information faster then then the speed of light? The article just got me thinking about sending information over long distances and wondering if It could decrease the lag time or eliminate it for sending transmissions from a space craft back to earth.
     
  7. May 20, 2010 #6
    Your question seems to be answered in the text you quoted. The measurements at each end are correlated, but individually random, entangled particles can not be used to communicate arbitrary information. The best you can do is use the correlation to share encryption keys used for decoding information sent on a conventional channel.
     
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