Stopping Light

Jon Abbott writes "NASA is reporting that physicists at Harvard University have managed to stop light altogether. The implications of this discovery are rather staggering -- quantum encryption and quantum computers might be just around the corner! " Well, I don't think this will mean any immediate changes - but it is a significant step.

Comments

They did NOT stop light!

[forand]

Ok this is just a point of fact: they did not stop light! They stored the information contained initially in a light wave in a new medium that they had control over, then were able to stimulate the medium to get it to re-emit.

Re:They did NOT stop light!

[Anonymous Coward]

It's been awhile since my quantum mechanics classes but I believe that storing all the quanum properties of a photon and imprinting them onto another is essintially the same thing as stopping and starting it.

Since a particle or photon is defined as the sum of all of its properties, if you are able to create another instance of the photon that has all of those properties, you've managed to duplicate the photon. It is, for all intents and purposes, the _same_ photon.

Fortunately, no two quantum particles can share the same properties. So as soon as you, form your duplicate, the original ceases to exist. (Technically, the uncertainty princple says that it ceased to be the same particle as soon as you started measuing the properties in the first place.)

Back when I heard about teleportation experiments they were doing just that. A photon's quantum properties were measured and imparted them to another photon some distance away. According the quantum mechanics, the photon teleported.

It sounds like a similar process may be happening here.

Re:Stopping light altogether?

[Telastyn]

From what I understand this is more akin to storage and retransmission.

The energy itself I believe is lost, though the waveform of the light, and its pattern is stored in the arrangement/orientation of the atoms. Shining another light into the atoms causes the eminating light to be of the same waveform/pattern.

A better analogy would be intercepting a streaming movie going across your network, waiting a while, and then re-transmitting it. You're not sending the same electrons, but you're sending the same bits.

Implications for Solar Power

[Niherlas]

So here's an interesting thought.

We can stop and "store" light.

So play blue-sky sci-fi author for a moment. Enormous dirigibles floating above the cloud layer, absorbing and storing light until "full", then coming to ground and offloading the light they've "mined" into solar cells (which no longer have to be laid out in flat arrays covering enormous fields) for conversion into electricity.

Hasn't that always been one of the problems, after all? There's plenty of bright, uninterrupted light available in the upper atmosphere, but the thought was always to convert it to electricity *up there* and somehow transmit the energy to ground level.

Maybe we'll just be able to mine the light.

Scary.

The worst part about this story

[sllort]

is not that it's a year old Slashdot repeat; we're used to that. The problem is that the whole "stopping light" headline that all the mainstream journalists (who should know better) carry on it is baloney.

If a photon (light) hits an atom (matter), causing it's electrons to move to a more excited energy level, I defy you to "show me the light". You can't. You can show me a really excited electron, and if you're really clever like these folks at Harvard you can even get that atom to release the exact same light with the exact same waveform, but you haven't stopped light.

It's annoying. How hard is it to say you've "trapped" light?

Things are going to change...very soon

[Orangedog_on_crack]

There are a handful new (or at least vastly improved) technologies that will be developed and put into use in the near future that will rival the changes ushered in by the developement of the microchip. This could happen much sooner than most people think, maybe as soon as 4 or 5 years. Quantum computing will be one. It will be crude and a lot of people will look upon it the same the that the Altair or the GUI developed by Werox PARC, but advances will happen fast once things get moving. Nanotechnology will be another. Tiny machines that can clean out clogged arteries will be "neat" but this will really be useful in materials developement. Once we can custom build materials at the atomic level, things will get interesting in a hurry. Being able to stop light is something that sounds pretty obscure, but then so was a little hunk of silicon Bell Labs touted 50 some years ago. I've talked to some people who were working in the electronics industry when the transistor was first talked about. A lot of them at the time thought "Well, that's neat, but that thing will never be able to handle any serious current. Intel made a real gamble in the 70's with their little "calculator-on-a-chip", the microprocessor, that they made in the hopes of selling it to a Japanese calculator manufacturer. It will be interesting to see what comes down the road from what these people did with stopping light.

Implications are staggering!

[sgage]

The Palestinian-Israeli conflict will be resolved, global warming reversed, and world hunger ended. I am definitely staggered.

(having one of those days when these sorts of breakthroughs seem ever so slightly irrelevant to the future of life on Earth - could you tell?)

Why are these headlines so misleading?

[GPS Pilot]

Next they reduced the intensity of the signal laser until the polariton was 100% atomic. There were no photons left inside the chamber.

There were no photons, people. They didn't stop light. Halted light would mean there are photons in there, moving at exactly zero meters per second. There were no photons left.