
Device can theoretically trap a light 'bit' for an infinite amount of time - quadfour
http://phys.org/news/2015-11-device-theoretically-bit-infinite-amount.html
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alpineidyll3
The article is totally misrepresented by this title, unsurprisingly. The
notable thing about the paper is that the authors found a way to exploit non-
linearity to separate pumping and emission with a particular nano-structure
which is impossible with linear optics.

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anc84
ELI5?

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alpineidyll3
Imagine the nanostructure as a bucket and light as water. The goal is to fill
the bucket with water and store it there. Light "fills" a material by
polarizing the electrons inside the material. However that polarization can
and must re-emit light. If there's a 1:1 ratio between the amount of
polarization you get in the material for field in the light the reverse
process is equally likely, then it turns out the material polarization will
always just make light again in the same amount as you add. Ie: there is a
hole in the bucket and you cannot fill it.

Some materials polarize non-linearly. Ie: you add 1 drop of water into the
bucket and it becomes two drops inside or the reverse. Actually all materials
do this but much less than ordinary (linear) polarization. The author's
contrived some setup which would exploit this effect to keep the polarization
in a nanostructure. Something like (and this is an abuse of analogy): one drop
in bucket, it splits, one of those is emmitted and one kept etc. The operating
principle of such a device is to control the paths the drops travel on, and
separate the directions to enhance the desired processes. Something like a
mouse trap.

There are many devices which already exist and maintain states of light given
some energy input, for example LASER cavities. Non-linear phenomena are well
understood and exploited in all sorts of fascinating optical devices. Non-
linear processes are usually weak and rare, so seeing them requires intense
light which is expensive to generate and can burn weak materials. Preparing
nanostructures which have the desired nonlinearities could be hard or
impossible.

For example it's easy to theoretically imagine a crystal that would take the
many of infrared photons emitted by the heat of your hand, and upconvert them
into fewer visible photons you could see. However any material which could be
polarized so much by those low energy photons would not be stable at room
temperature so no such thing exists...

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tantalor
Humans normally use the word "permanently" to describe this condition.

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warfangle
"Permanent" has a very different meaning from "infinite amount of time."

Permanent implies that it's irreversible, and this is definitely not the case.

Given that the gain element must be employed for the storage of the light, and
the removal of the gain element causes the release of the light, it is not
"permanent" \- it is "potentially infinite, as long as the gain element is in
place."

That makes it useful for research into all-optical computation.

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gizmo686
Theoretically, the gain element is not necessary. They only need it to
compensate for physical imperfections in the device.

