Teleportation Just Got Easier, But Not For You

Whether or not you’ve ever been on a long-haul flight, you’ve probably fantasised about being able to magically disappear from one place and reappear in another. And a natural question for a physicist is whether there is any way to achieve this in practice. Thanks to two studies published in Nature last Thursday, the chance of successful teleportation has considerably increased. Which is a good thing, right?

In fact, something known as “quantum teleportation” became a reality in 1997. This first demonstration was for particles of light (photons). Since then, physicists have also applied teleportation to other very small things, for example single atoms.

So when can we expect to just teleport ourselves to our chosen destination? You might want to sit down for this.

The first step to teleporting a person is measuring and recording the position, direction of motion and energy of every particle in the body, which would require more data storage than will ever be available — much, much more.

In fact, a conservative estimate would mean you’d need about 10 to the 22 gigabytes (1 followed by 22 zeros) of hard drive space. That’s a stack of hard drives about 20 light-years tall.

Proxima Centauri, the nearest star to Earth other than the sun, is around four light-years away.

Worse, we have no method to even make these measurements, let alone reconstruct a person based on the data. So we can forget about teleporting people.

Knowing enough – but not too much

What about something really simple – such as a single particle? How about an atom, or a photon? How can these be teleported?

The problem here was thought to be the Heisenberg uncertainty principle, a cornerstone of quantum mechanics that limits what you can know.

It might sound counter-intuitive, but if you try to measure the position of a single atom you will change its velocity. If you find out exactly how fast it is moving, then you won’t know where it is.

The problem is, if you want to teleport a particle, this is precisely the information you want to measure and transmit.

A physicist would call this information the “state” of the particle. If you’re not allowed to measure the complete state of the particle, teleportation looks impossible.

So the key to teleportation is not knowing too much. As long as the measurements that you make do not reveal the position or velocity, then you have a loophole that allows you to circumvent the uncertainty principle.

What if you could disturb the particle before you measure it, so you never know its state, and then subtract off that disturbance at the other end to recreate the original state of the particle?

This was the breakthrough realisation that American physicist Charles Bennett had in 1993. The key was to disturb the particle you want to teleport in a particular way. You can do this by using a pair of quantum-entangled particles.

These particles are linked to each other so that if you measure the state of one of the entangled pair, you learn about the state of the other half of the pair.

Alice and Bob

In the standard description of teleportation, Alice is teleporting something to Bob. Alice uses one of the entangled particles to measure the state of the input particle. She records what she measures and sends the information to Bob.

Bob can’t tell what the state of the particle was, because the entanglement used in the measurement hides the true nature of the state.

What Bob can do, however, is use the information from Alice to modify the state of the other entangled particle. In this way he can recreate the exact state of the particle Alice originally measured.

This is how quantum teleportation works. Most photon experiments teleport over a metre or so inside a lab, although there has recently been a demonstration over 143km in the Canary Islands.

A sense of security

It turns out that quantum teleportation is not just a good party trick. The nature of the communication between Alice and Bob in this system is pretty interesting.

The information that Alice measures and sends to Bob cannot be used to recreate the input state without the other entangled particle. That means Eve the eavesdropper can’t spy on Alice’s measurement and get the information for herself.

The entangled pair is unique, so only Bob can recreate the original state. Immediately you have a technique for secure communication.

If you encode information in your particles, measure them with one part of an entangled state and then send the information to Bob, you have cryptography that is made strong by quantum physics. You really can’t crack it by any means, unless you have the other part of the entangled pair.

Reasons to be cheerful

Teleportation has many other uses in quantum information systems.

These are proposed methods for building computers and communication networks that use quantum mechanics as a core part of their functionality and have enormous potential to provide secure communications and high-speed computing.

The catch is that any time you want to move quantum information from one place to another in one of these systems, you can’t just measure the information and send it to the next part of the process, since the measurement will destroy the information. Instead, you can teleport it.

Back to Nature

The two papers published together in this week’s Nature show something very important.

Until now, teleporting photons of light using the method described above has been probabilistic, because you couldn’t synchronise the arrival of the entangled photons with the arrival of the photon to be measured.

On the odd occasion when the photons aligned, the measurement would only work half the time. That means every time you try and teleport your information it will only work very occasionally – much less than 1% of the time.

If you have a lot of back-to-back-teleporting circuits in your quantum computer or quantum network, the chances of them all working together will become vanishingly small.

These two most recent experiments show deterministic quantum teleportation in two different systems so that the process is no longer probabilistic. Instead it can, in principle, work every time a photon is ready to be teleported.

One of the new studies – by researchers from Japan and Germany – shows how it is possible to teleport photons of light that are in the infrared spectrum, just below the wavelength visible to the human eye.

The other experiment – by researchers in Switzerland and Australia – demonstrates teleportation of microwave photons with a frequencies between 4 and 7 GHz.

Neither system is production-ready, in the sense that they are both just proof of principle experiments. Although the teleportation is no longer probabilistic, it is still not 100% efficient – a 40 per cent chance of success in the case of the infrared system and 25 per cent in the case of the microwave system.

Still, this is a vast improvement on less than 1 per cent that was previously possible with photons. Long-haul flights will continue for some time yet, but the new experiments represent a milestone on the long road to building a functional quantum information system.

This article was originally published at The Conversation. Read the original article.

Teleport image via Shutterstock


Comments

    The main issue I have with teleportation is the classic "Will it be the same you at the other end or an exact copy of you while the original you died from the teleportation dematerialisation (and therefore not your conciousness, simply another conciousness that is precisely the same as you, except you're not in control of it as you are dead)?"

    D: Not sure if I'd want to try it, even if I was alive when it was perfected

    Last edited 19/08/13 11:17 am

      Thats a question for philosophy to solve, not science.

        How do you figure that..?
        If they develop a method to transport humans it would have to be a direct transportation, not a copy. which includes everything including the "thing" that is in charge of the body...! Whether or not that "thing" actually exists, first it would need to be proved to exist... hence science, not philosophy.

          The method of teleportation described in this article is essentially a "recreation" method. It doesn't instantaneously transport anything anywhere, it uses measurements of particles to know how to re-create them at the other end.

          So the question becomes, if something a person is an exact copy of the original, down to the very smallest possible detail, are they the same person? Science say's no, because they're made up of new particles at the other end, those particles are arranged the same way, but they aren't the original particles. Philosophy could argue that each person's brain and thoughts are unique, so recreating them somewhere else will re-create the same person (of course there would be endless philosophical arguments about this).

            I've written something about this to your comment below... :)

      Teleportation, in this context, is a destructive process. The original is destroyed in the process and recreated at the target side. The teleported being would believe it was the original, but it wouldnt be, but that might be good enough.
      Its also worth noting that all humans change their molecules every 7 years, so technically what "you" are changes many times over a lifetime, so this could just be a more radical extension of this rationality.

        On that note, would you use teleportation with the knowledge that it "kills" you?

        I wouldn't =/

        That depends if the "new" object is constructed from the same atoms as the old object, or if is a copy.
        There are different schools of thought.
        Do you actually destroy something if you break it down to it's component pieces? What is the definition of destroy? =P
        I don't think the theory is defined enough to answer this one way or another.

          yes, but "you" are not your atoms. It doesnt matter if the atoms are the same or different.

          Think about it like when you digest something. All you are doing is breaking it down and (through conservation of mass/energy) converting it to another form. Most would agree that digesting something, destroys it, even though it technically still exists in another form.

      Exactly... everyone else would see you as the same person, but you would have been killed in the process. I've tried explaining this to friends and sometimes the only way they get it is if I explain "What if the machine stuffs up, reads your body but doesn't destroy the original and a clone pops out at the other end... you can't control the clone, there are now two of you... if the machine had worked, there would just be the clone and you would be dead"

      I'm thinking it would be more prudent to focus efforts on a wormhole or similar, where matter isn't read, destroyed and recreated but rather moved instantaneously by connecting two points in space time together???

      That's why I'd prefer the "wormhole" method of teleportation.
      Create a door between two locations, rather than destroying an object and re-creating it somewhere else or breaking something down into atoms and re-building it.

        Yes, this is preferable and the only non-destructive way of teleportation. All it does is link two 3D points in space
        However, and its a big however, the amount of energy required to create a wormhole is monumental and the fact that we do not understand how to absolutely address a 3D point in space considering we still dont understand what "space" is. Also, there would likely be time dilation effects associated with passing through a wormhole. You could arrive at your destination, but a million years in the future.
        But solve those two logistic and knowledge gaps, then you've got a viable teleportation method.

          That's all speculation. We don't know enough about bending time and space to gauge how much energy it would take or if time would play any role.
          Perhaps there is a way to lock the co-ordinate system around the earth, or the sun. That way your wormhole would be relative to "space" just like you and me are right now.

          Anything is possible until proven otherwise.

            good point. we dont know universal absolute addressing, but we could make it relative to a known point (ie. earth) and compensating for expansion.

    The biggest problem to solve in teleportation is not the amount of data to send, but how to capture and re-compose the object/human at the other side - instantly. If it is not instant (ie. zero planck-units in length), the energy/information recorded in the snapshot will not mesh together correctly at the other side.

    Therefore, teleportation as we currently understand it is not possible. Duplicating items (or a close approximation of) digitally from one location to another is feasible, so long as it isnt alive (and you want to keep it alive).

      I think there's a possibility they will eventually figure it out for non animate objects but not live ones... :)

        The big this with this "rebuilding" or "reconstruction" process for inanimate objects is that if you already have the technology to rebuild objects from data.... why would you need to send any data at all.

        What you have then is an atom level 3D printer.

        Hell, we'll probably be able to 3D print bio-matter soon anyway, so the real problem is the transfer for conciousness, thought and souls etc...

          but you need to be able to do it instantly. 3d printing something organic is fine, but how does something live while it is only partially printed?
          consciousness is only neural configuration. Thought and souls are thought to be only neural activity. If we can snapshot it, we should be able to recreate it (in theory).

          so the real problem is the transfer for conciousness, thought and souls etc...

          Those are nothing more than electrical impulses in your brain, and would be captured just the same as a particle level information is captured.

            See, that's where the philosophy comes into it isn't it?
            The impulses you're talking about are the same thing as a computer talking to it's relative bits and pieces, Ram, CPU, Graphics etc. The Brain does the same thing, Memory, sight, calculation etc. The soul for want of a better word is the driving force... the original and only you..!! Generally thought to come from outside of the physical not inside. Oh and I am the furthest you can get from being religious, so it has different connotations for each individual.. :)

              You're transmitting every particle in your body and re-assembling it in the exact same way at the other end. Anything that defines "you" would be re-created exactly. That would be any of these philosophical attributes, conscious, thoughts, souls, they're all just a part of your brain, how it's wired up, and the electrical impulses going through it at that moment. There are no "outside" influences on your brain, other than environment, which changes due to the fact you're travelling, not because you've been re-assembled.

                In order to duplicate a human brain exactly though, we will need to fully understand quantum states and any other dimensional properties that mass has. We are still a long way from that.
                I doubt that a soul exists in any other capacity apart being a function of consciousness (which is just neural configuration).

                No, None of your "body" gets transmited. The first the machine reads the position, velocity and direction of evey atom and subatomic particle in the body. The atoms and subatomic particles are then converted to energy. This energy can be used to power the machine. The information gathered by the machine about the position of your atoms is then transmited to the second machine which reads the info then converts energy into matter to recreate the object. The same can be used to replicate things. have a great steak? run it through the transporter and record the data. Then you can reproduce that steak over and over again, and as the man said, no animals were hurt in the making of this burger so the vegans can go choke on their tofu.

                  @moonhead @villainsoft @tonyintsv
                  I get what your saying, but what I'm saying is that there is no detectable particles (yet) to prove the existence of a soul (or whatever). I like to think of it this way- a computer's soul is the operator, essentially.. 'you', and you are outside the machine! The human brain is a computer and "you' are outside the machine! I realise that's getting into metaphysical but I also believe there are many more dimensions and universes than we can currently see, so it may sound or even be preposterous, but it is possible... :) BTW.. good banter... love it..:)

                  Last edited 20/08/13 8:58 am

                Yeah, your missing my point.. I'm not talking about anything that can be reproduced, I'm talking about the meta physics of it all, not the physics. I guess it comes down to whether you are a spiritual thinker or not. And I'm not talking religion, just whether you believe that your soul is real or not.. :)

                  You either exist or you don't exist. If these particles that comprise all the metaphysical attributes of you don't exist, then they won't be missed, if they do exist then they'll be re-constructed just the same as every other particle.

      If they could manage it for large inanimate objects that alone would be an amazing advancement, the impact it would have on space travel and colonization alone would be immense. There's not overly much use in teleporting anything living that's not human and obviously there's tons of problems with that (scientifically and philosophically).

      This article though is mainly about quantum security since it's focusing on microscopic amounts of energy/matter, there would be no practical purpose to teleport that aside from encrypted communication since pretty much any other method of transport we currently have would be more efficient (although I guess there could be some use in transporting exotic matter with extremely short half-lives).

      I'd love for there to be a major advancement in teleportation of 'macro' objects because space stations, asteroid mining etc would all become so much more practical but I think that one maybe quite some time away sadly :(. Hell energy to matter converters (true replicators) maybe a more realistic goal ^_^

    Not sure about the science of this, but isn't everything basically just energy? Can we not just treat the matter as though it were energy and transmit that? Then it's just a matter of bandwidth! (Hmmm. Better get FTTR in the NBN or I'll never get to work!)

      Except for conservation of mass....

        And the fact that conservation of matter was exceded by relativity then special relativity means nothing? That it was a theory that was first discussed by Greek philosiphers and alchemists 400 BCE? That Quantum phisics states that matter and energy are the same thing?

    The other way around the Heisenberg uncertainty principle is to remove the velocity from the equasion. cool the object being transported to absolute zero and all particle motion stops. Therefore, since the matter is at reset, finding the where will not change the when.

    Another important implication of this technology is that if you record the snapshot of the object you want to teleport, you no longer need the original object.
    You could create it again and again. A cloning device which would be a serious threat to global trade economies.
    This teleportation technology could also, inadvertently, provide a method for humans to live forever (or at least, over an over again, forever)

    Even if it was possible to teleport, we'd risk getting mixed up with any stray bacteria that entered the porter and come out looking like me at the other end.

    OK so teleportation is out, that just leaves worm holes and space folding. Come on scientists, hurry up. I am so over the NSW transport system!

    Someone had to check the maths (albeit a few days too late)

    Light year in metres: 9460730472580800 m

    Height of desktop HDD: 0.0254 m (taken from WD site)
    Max (current) data per HDD: 4000 GB (4TB)

    Data required: 1x10^22 GB
    # HDDs required: 2.5x10^18
    Total height of stacked HDDs: 6.35x10^16 m
    Total height of stacked HDDs in light years: 6.71

    That's about 1/3 the height of these stacked HDDs than the article says!

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