Teleportation the cool way.

[Corpse]

Been away for quite sometime but every now and then, I come across something I feel compelled to share.

There has been a lot of research carried out on teleportation involving quantum entanglement since the late 90's; the Australian Research Council Centre of Excellence for Quantum Atom Optics (ACQAO) has found a new way which does not involve quantum entanglement, instead using Bose-Einstein Condensates.

Article from New Scientist.

Teleportation of Massive Particles

13 June 2007

When an object is transferred from one location to another, by a method other than physically moving the object itself, it is said to have undergone "teleportation". A fax machine might be said to teleport a piece of paper, but it doesn't have perfect resolution, so the paper you send to the receiver is always a little different to the piece you started with. You might think that measuring the paper with increasing accuracy might eventually lead to the perfect 'teleporter'. If you get all the atoms exactly positioned, it doesn't matter if they are the 'same' atoms as the original piece of paper, because quantum mechanics dictates that all particles of a given "type" are fundamentally indistinguishable (i.e., the universe is exactly the same if you swap two electrons).

Unfortunately, quantum mechanics, in particular the Heisenberg uncertainty principle, dictates that we can never measure the quantum state of a system perfectly. This "quantum noise" will make it impossible to accurately teleport something.

However, in 1993, a team of Physicists (C. H. Bennett, G. Brassard, C. Crépeau, R. Jozsa, A. Peres and W. K. Wootters (read the original paper here), devised a scheme to avoid this problem by using quantum entanglement. Quantum entanglement is a bizarre property of quantum mechanics. When two particles are entangled, measurements on one of the particles instantaneously effect the quantum state of the other particle, no matter how far away it is. Entanglement is used to implement quantum teleportation as follows:

The sender (usually referred to as "Alice") combines the particle she wants to teleport with one half of an entangled pair of particles, and then measures the properties of the system, disrupting the quantum state of the system in the process. The added quantum noise from this process 'hides' the original quantum state from Alice. She then sends the results from her measurement to the receiver (bob), who possesses the other half of the entangled pair. Bob then uses this information to perform operations on his half of the entangled pair to retrieve the original quantum state. This works because the quantum noise of his half of the entangled pair is exactly right to cancel the noise added by Alice's half. Experiments using this scheme, or variations of it, have been performed with single photons, beams of light (also done in the first Australian teleportation experiment) , trapped ions, and the nuclear spin states of an ensemble of atoms.

In theory this scheme can lead to the quantum state being perfectly teleported. However, in practice quantum entanglement is never perfect, and this limits the fidelity of current teleportation experiments. So far, teleportation experiments have been limited to a fidelity of 85%.

Thanks to Heisenberg's uncertainty principle.

Our scheme is different as it does not rely on Alice and Bob sharing quantum entanglement. We have shown that it may be possible to teleport a group of about 5 thousand cold atoms by transferring their quantum state onto a laser beam, which is then 'beamed' to a new location where the receiver can use this laser beam to recreate the original group of atoms almost exactly. The scheme relies on the sender and receiver each having a reservoir of extremely cold atoms, known as a Bose-Einstein condensate (BEC). BEC is a state of matter that occurs when atoms become very cold, (about 100 Billionths of a degree about absolute zero). Due to a phenomenon known as Bose-Enhancement, all the atoms like to act the same way. This causes the atoms to act as one macroscopic matterwave, rather than a collection of individual atoms.

This is what makes BEC's fascinating, you have a collection of atoms (bosons) gathered in a single quantum state forming a super-particle which behaves like a wave and in which other quantum properties are observed at a macroscopic level. One of its interesting properties is that light travels slowly through BECs. This is just a speculation but it is possible that some of the dark matter in the universe (which could be in regions of space propitious for this forms of matter to occur) is made up of BECs or some other similar form of matter in a single quantum state.

There is a sixth state of matter which is equally fascinating known as the fermionic condensate. In this fermions are gathered in a similar quantum state... however unlike bosons (which have even numbers of protons, neutrons, electrons), fermions (which have odd numbers of these particles) cannot gather in a single state due to Pauli's exclusion principle. However, a scientific team from NIST found a way around this 3 years ago by using pairs of fermions. In this form fermions behave like bosons and gather to form a fermionic condensate which exhibits properties such as superconductivity (which could be used for room temperature superconductors), superfluidity, etc.

Anyway, going a bit off topic here.

Our proposed scheme is illustrated above. We consider atoms that have three internal electronic states (which we will label (|1>, |2> , and |3>). Atoms in state |1> experience a force due to magnetic fields. By applying an appropriate configuration of magnetic fields, it is possible to contain state |1> atoms in a magnetic “trap”. BEC is usually confined in a trap by this method. Atoms in state |2> do not experience a force due to magnetic fields. State |3> represents an excited atomic state. The separation in energy of state |3> from state |1> and |2> is about the same as the energy carried by an optical photon. By transferring atoms from state |1> to state |2> in a controlled fashion, atoms can be made to slowly leak out of the trap and form an Atom Laser.

We begin by sending a pulse of atoms in state |2> towards a trapped condensate (made up of state |1> atoms). It is the pulse of state |2> atoms that we wish to teleport. The condensate is illuminated with a laser beam (called the control beam) which is of the correct polarization to couple atoms from state |2> to state |3>. However, the control beam is slightly detuned from the exact resonance. When the atoms encounter the control beam, they absorb a photon, transferring them into state |3>. This state is unstable, and ordinarily the atoms would rapidly emit a photon in a random direction from this state, and end up back in state |2> or state |1>. However, due to the presence of the BEC, and that the control beam is slightly detuned, the atoms are stimulated to join the BEC, and thus emit a photon such that they all end up in state |1>. As all the BEC atoms have a very well defined momentum, conservation of momentum dictates that all the photons must be emitted in the same direction, forming our signal beam. By careful adjustment of the intensity and wavelength of the control beam, we can arrange it such that the quantum state of the atomic pulse (i.e., the position and momentum of each atom, or, equivalently, the amplitude and phase of the atomic matterwave) are encoded onto the signal beam. Ideally, the number of photons in the signal beam is exactly equal to the number of atoms in our original atomic pulse.

This information is then 'beamed' to a second BEC, which is also illuminated with a control laser. The atoms in the BEC absorb a photon from the signal beam, and are forced to emit it into the control beam due to stimulated emission, transferring the some of the BEC atoms into state |2>, where they are kicked out of the condensate due to the momentum of photons. As the information of the original atomic pulse is transferred to the new pulse, we have effectively teleported our original blob of atoms.

Read the full article from ACQAO.

So there you go, with every new discovery, the age of Star Trek could be a lot closer than we think. If we manage to survive to see tomorrow that is.

 

[Sorrow]

I doubt a teleportation of living beings would be ever possible. Not when the process involves killing the original and then creating it's copy.

 

[Xombie]

I remember seeing in a link from abovetopsecret.com to some techie site that detailed an experiment which managed to produce a teleport-like effect with some minor particles. But i damn it if i can't recall the article well.

 

[Corpse]

It will be a very long time (if ever) before teleportation of molecules, let alone more complex forms such as organic matter; its one more step towards this goal.

One disadvantage this system has is that matter is limited to travel at the speed of light, where quantum entanglement offers an instantaneous response regardless of distance between entangled particles.

 

[Arachnivore]

One disadvantage this system has is that matter is limited to travel at the speed of light, where quantum entanglement offers an instantaneous response regardless of distance between entangled particles.

Not quite true. Teleportation via quantum entanglement is still limited by the speed of light. It requires a classical communication channel.

The complexity of teleporting even simple organisms pretty much demands sophisticated quantum computers. What's interesting is that these early teleportation experiments are supposedly laying the foundation for quantum computing.

I doubt a teleportation of living beings would be ever possible. Not when the process involves killing the original and then creating it's copy.

You aren't really being killed. Your just moving really fast to a new location and getting a brand spanking new set of atoms along the way

 

[Goweigus]

Michael Crichton's : Timeline
(movie does a poor job of explaining but the book has some interesting ideas and shit)

 

[Corpse]

Not quite true. Teleportation via quantum entanglement is still limited by the speed of light. It requires a classical communication channel.

True, I guess I was making a bit of an assumption there; I do that a lot.

The complexity of teleporting even simple organisms pretty much demands sophisticated quantum computers. What's interesting is that these early teleportation experiments are supposedly laying the foundation for quantum computing.

Indeed, and quantum computing is another area where these "supercold" states of matter I mentioned may become a big part of their development as you can see here.

 

[Arachnivore]

The complexity of teleporting even simple organisms pretty much demands sophisticated quantum computers. What's interesting is that these early teleportation experiments are supposedly laying the foundation for quantum computing.

Indeed, and quantum computing is another area where these "supercold" states of matter I mentioned may become a big part of their development as you can see here.

Actually there are a few schemes devised to allow quantum computing at room temperature. One of which uses diamonds.
I just can't wait until I can have my own quantum computer with lasers and diamonds and teleporters