I was thinking that we are getting very close to quantum computing. if not that then perhaps this may speed up fiberoptic speeds by being able to stop and "program" the light at your node and then send it on its way. everyone should be proud as i am refraining from using any puns about IM. :-)



Light 'frozen' in its tracks


18:00 10 December 03

NewScientist.com news service

A pulse of light has been stopped in its tracks with all its photons intact, reveal US physicists.

In a vacuum, light travels at the phenomenal speed of 300,000,000 metres per second. Scientists can exploit the way that the electric and magnetic fields in light interact with matter to slow it down.

Over the last few years, scientists have become masters of the light beam. Speeds of a few metres per second are now reached routinely in laboratories around the world. It is rather harder, however, to stop light completely and previous attempts have halted light but lost its photons in the process.

Mikhail Lukin and colleagues at Harvard University in Cambridge, Massachusetts managed to stop light without this loss by firing a short burst of red laser light into a gas of hot rubidium atoms.

This is then "frozen" with the help of two control beams. The light in the control beams interacts with the rubidium atoms to create layers that alternately transmit and reflect the pulse.

As the signal tries to propagate through these layers, the photons bounce backwards and forwards between them. As a result, the pulse makes no forward progress - the light is "frozen" in place. The pulse is set free when the control beams are turned off.

Ulf Leonhardt at the University of St Andrews in Fife, Scotland, says the technique is novel in that the effect the control beams have is "like storing light behind bars".


Fractions of a millisecond


In 2001, two groups reported they had stopped light (New Scientist 08/08/01). Lukin was involved in one of these experiments, the other was led by Lene Hau, now at Harvard.








Both teams slowed light down by passing it through a gas of atoms. Lukin used hot rubidium atoms, Hau super-cooled sodium. Both managed to reduce the speed of light to zero however, by the time it had slowed to a halt, all of the photons had been absorbed. The pulse could be regenerated because the photons' energy was stored in the atoms. But while the pulse was stationary, technically, it contained no light at all.

Lukin and colleagues Michal Bajscy and Alexander Zibrov have so far managed to hold light still for just fractions of a millisecond using their new method. But there is no reason why it cannot be trapped for longer, they suggest. This could be a useful trick to employ in telecommunications systems that send optical signals, or more fancifully, in quantum computers.

"Frozen, stationary pulses of light mark a new chapter in quantum optics," comments Marlan Scully at Princeton University, New Jersey in Nature.

Journal reference: Nature (vol 426, p 638)

Can you give us the link to your source on this? I am interested.

http://www.newscientist.com/news/news.jsp?id=ns99994474

Hope this helps

I read about the 2001 experiments last year during a class I took in Optics, though we concentrated more on the immediate practical applications that this presented, which were quite astounding in themselves. Things like boosting and attenuating optical signals with no loss and much more efficiently than currently possible.

any intresting links to share from that experience? i am into this stuff and I would love to see more. BTW did you cover line of sight or was it mainly fiber optics?

I read somewhere they are talking about making new optics out of a balck widow spider's webbing. Sicne it is so small it was the perfect source. They coated it with some sort of material, then burned the webbing out of the middle of it to hollow it out completely, and it had quite an increase in performance since it was traveling through air. I haven't heard much about it recently, but it sounded great back then.

I couldn't find any links, just some of the notes from the lecture and discussion. I'm sure you wouldn't want those, though you probably already got a good summary of the same material we discussed.

The class I took dealt with a lot of fiber, as most of us were taking it as a further study after taking courses in fiber, though line of site was covered in the fiber optics classes I took as well, along with much more that I have never put to practical use. Though much has changed between the time I took the first course in optics(12 yrs ago) and the one I took last year.

Poert, I believe we discussed that spider web fiber once in the channel, I remember talking with someone about it, and we had also talked about it in class last year. I remember something about the hollow channel would cut out refraction, thus retaining all of the original signal almost indefinitely(or something close to that anyway)

That is exactly it. Using a hollow transfer medium rather than a solid one would allow for a virtually unlimited distance of travel because when it is traveling through air, there is nothing to refract the light off of, unlike the current technology. I think this will be very interesting to see what happens in the near future.

I imagine it will be difficult to prevent particles which would degrade the signals. How would they ensure that the burn web bits had been removed? 1 bit stuck to the wall at test time may not appear, but may unstick and cause problems down the road. it would be like finding an electron in a haystack or some such.

Thats pretty cool but why would we want to do this in the first place?

Which the stopping of light or the hollow tube?

The idea of both may be the possiblity to use light as a data stream thus making the internet lightspeed. you would also have practically unlimited bandwidth as one strand can hold a huge amount of "channels" and the fibers are usually clustered into groups of say 100. This way downloading files such as halflife 2 would take 2.2 seconds ( assuming it takes you two seconds to click download )

Gosh that would be revolutionary :eek:

You'd need your hardware to be able to handle that amount of data bandwidth. Good luck with today's hard drive technology.

I just use my quantum processer , which at first will use atoms in a charged state raise to the next level which will be read as a 1. i will do this with a processor the size of a pin head, which should hold enough atoms to safely handle the storage issue. i would like to upgrade to the quark drive processor, but I am having problems with compatablity on my MS win VR system. i kicks me out of virtual mode and I get sent to the XP based safe mode. None of my touch sensors work, and i have to go back to using a "mouse" lucky my grandfather kept that antique in the basement....