Saturday, May 30, 2009

Teleportation –from Fiction to Reality?

“Beam me up, Scotty”, who hasn’t yet heard this phrase from Star-Trek? Beaming – alias teleportation –is a favored part of many science fiction stories and thus well-known by publics. Probably most of us would like to have a teleportation tool, for saving stressful traveling time, or to experience famous adventures on alien planets… During the last ten years you may have heard that scientists have successfully entered the field of teleportation. But, is it the same teleportation as in Stark Trek? Let us find out what fiction is and what to reality belongs.

In Star Trek, humans and materials are teleported with superluminal speed from one place to another – empty - place. Thereby, teleported is the matter (atoms) or energy and the information in which state the matter is. Mostly, the teleportation process is controlled by a station which can act as receiver or sender. In Science things are a bit more complicated as usual, but the good news is that there exists no physical law which prohibits the teleportation of humans – it is only quite complex to do so. Today, mostly single photons are teleported. Contrary to Star Trek and similar, in reality you can teleport only the information of a state and not its matter or energy. As a consequence, you need at the receiver place already the same type of matter/ energy onto which you can overwrite the state of the particle which you want to teleport. Furthermore, you can´t do it with superluminal velocity, hence no causality violation. The reason is that the particle at the sender and the one at the receiver´s place have to be specially prepared, namely to be entangled together. The entanglement allows the teleportation of the state of a particle with superluminal velocity (Einstein called it “spooky action at a distance”) but to read out this information for further processing, the receiver needs some special information from the sender -after he performed a special action to the particle- which he can get only with not superluminal velocity (by phone etc). Another point is the entanglement process for more complex systems. Photons and ions are routinely entangled, but even simple molecules are very hard to do so. To my knowledge, single Buckminsterfullerene (C60, 60 carbon atoms) are the biggest systems which have been entangled (diameter around 0.7nm). But they haven’t yet been teleported, because as larger an entangled system is, as shorter the duration of the entanglement state. Now, imagine a human body and you will understand why it is quite difficult to teleport us. Hence, “beam me up, Scotty” has to stay for longer time in fiction.

These days, teleportation in the lab with photons is already routinely done. The teleported distance increases continuous and is over 100km for teleportation in free space as in fibers. Furthermore, teleportation using ions (spin) have been demonstrated too. In future, scientists are planning to teleport larger atom complexes (fullerene) up to small bacteria. But until this time has arrived, new techniques have to be developed.

Nevertheless, theoretically humans could be teleported but the question arises, if our body is teleported, will our spirit, our soul be teleported too? Nobody knows.


Video from the teleportation group in Geneva (in french):



Links to teleportation groups:
Geneva, Prof. Gisin
Munich, Prof. Weinfurter
Vienna, Prof. Zeilinger


Tuesday, May 19, 2009

Pink is not a colour


Have a look at the visible spectrum; you can see many colours: red, blue, green, yellow... but what about pink?
You can not find it in the spectrum... but then, why do we see it? Basically, we could say that the reason is just the difference between wavelength (property of waves) and colour (asigned by the brain).
When the eye perceives just one wavelength (for example 600 nm), our brain identifies the colour of that wavelength (in this example, red).
But, what happens if the eye receives light of more than one wavelength? In this case, the colour interpreted by the brain is usually the sum of the input responses on the retina, i.e. the colour halfway between them... except when the wavelengths come from both ends of the light spectrum at once (i.e. red and violet light).
In this case, the colour halfway would be green (not very representative of the mixture), so the brain simply invents a new colour halfway between them: pink (or magenta, according to its official name).
This post has been adapted from http://www.biotele.com/magenta.html. You can find there a extended version.

Thursday, May 7, 2009

Ultra-Fast Dynamics Imaging


Hi, my name is Camilo Ruiz and i am special correspondent sent to the island of Ischia close to Naples Italy for the conference Ultra-Fast Dynamics Imaging celebrated from 30/04 - 03/05 in 2009.

This small workshop was organized by the local group at University of Naples and many of the most important players in the attosecond science were invited to participate. While attosecond is all about precious stability only achieved in well equipped and rich labs, everybody was happy to be invited to the southest part of Europe, where the sun is always there and there is not much of a rush, so we had a perfect combination.



The full program of the conference as well as the book of abstract can be found in the conference web page , i will instead point out some of the topics that i liked more together with some references.

On wednesday 29th, we had several good results. From the University of Frankfurt, Reinhard Dörner presented a paper on "Inteference and electron entanglement in photoionization of H2 and N2", this work is published in Science recently and explore the question of electron localization: When a diatomic molecule absorb a big photon a hole is produce because a k-shell electron is ionized, but then the question is weather the hole created is localized or not. In the case of the hole being localized, the electron hole should hope in 20 fs, later in time an Auger electron should be emitted to fill the hole. If this electron is emitted from one electron only, it should be diffracted but if it is not localized, probably the diffraction will be vanished.

Quotimg the reference: "Whether the core hole is better thought of as being localized or delocalized depends on the direction in which the photoelectron or Auger electron is emitted. Detecting the direction of the photoelectron in the experiment selects between cases in which the transient core hole is best described by a delocalized state of g or u symmetry, and other cases for which it is more appropriate to think of a localized hole. This situation can be described by a coherent superposition of gerade and ungerade states, or alternatively by a superposition of states corresponding to a hole on the left and one on the right."

Certainly there is more to it, as the enviroment breaks this description, but as expected the answer is very quantum like. These are beautiful experiments which don't even need a fast pulse, these are synchrton radiation only. Will time might play a role? Lets find a 419 eV photons in a short pulse to answer that.

The gropu of Garching talked about the new set of experiments in solid interfaces, these are very interesting results, more interesting is the new rout of this leading lab which will concentrate on multiple streaking. As this is something i am also doing i will not mention anything more about it. But try this paper.

These are just two talks, so you can imagine the number of things happening. The next message might be about the new XFELs around the globe.