I have googled this question, and it was previously discussed on Physicsforums with a miserable response. (Not posted by myself) http://www.physicsforums.com/archive/index.php/t-125299.html Can sciforums do better?
If you mean take the energy of some photons and convert them into some other form of energy and store that then yes. If you mean trap some photons and hold them in one place then no, because photons have to travel at c in a vacuum. In materials that are close to "opaque" to photons they travel much slower on average but that's because they are absorbed and re-emitted continually
I suppose you could always trap a photon between two closely-spaced reflective devices like mirrors, so that it just keeps bouncing back and forth between the two. I know they have various ways of trapping ions and other particles, I'm sure a scheme like this has been done with photons before for one reason or another. If you mean trapping a photon by holding it in exactly one place, then no, as Prometheus said a photon always travels at \(c\). It can be repeatedly absorbed and re-emitted in a material to give the appearance of travelling more slowly, but any time the energy is stored in the form of a photon, it's always going at \(c\).
I asked the question because it occurred to me that a photon battery might be handy. There is a problem with heat production if they are crowded into too small a space. For example, with a magnifying glass. Ants were the usual target in my boyhood. Can they be kept cool in any way? One more reply and we've equalled physicsforums.
OOh, maybe Bose-Einstein condensates are relevant here, iirc they can 'slow' photons, although I think it falls short of trapping them? Anyone real physicists care to dust off my rusty recollections?
One way I thought photons could be stored is inside a fiber optic ring. There could be a little technical problem to solve in how to insert the photons in the ring and how to take them out when needed (I suppose the intention to store them is to use them at some time).
In order to get decent lifetimes for the stored photons you would need a mirror and vacuum set up rather than a total internal reflection set up. Total internal reflection requires that the photons travel through a medium other than vacuum which would inevitably lead to quick attenuation. If you had some very very shiny mirrors and you put them in an enormous vacuum, you could potentially store photons for up to a second. martillo- this is a good point, it would be very difficult to add and remove photons from any such setup . One could couple the fiber, but it would have to be done at tiny time scales so that photons would not get out-coupled right after being in-coupled.
Quite simply you can't store a photon. If you generated equipment to bounce, circle or encapsulate a photon, you'd find that you would have to invest external energy into "capturing it". so technically it wouldn't be the photon you initially captured. The closest I would suggest you could get is allowing photons to generate chemical reactions, like in photography. You aren't of course capturing a full photon, just a reaction of an instance. (and that instance is actually spanned in time by the chemical reaction, since it's not actually instantaneous.)
Actually storing photons is a topic of research; they can stop light as a pulse, in condensates, and I remember reading about storing and recovering like, 25% of a photon in a phonon for a few nanoseconds. There is research because a way to use light to switch light means you can build circuits. Storage is needed to calculate or copy stuff, and nanoseconds is a long time. The thing is capturing the 'bit' is the important part, it doesn't matter in digital circuits if the signal is degraded as long as you can read the digits.
I've just read the wiki article on Photons. http://en.wikipedia.org/wiki/PHOTONS It may be factually correct, but I doubt it. It is very badly written. Example sentence: The effects of this force are easily observable at both the microscopic and macroscopic level, because the photon has no rest mass; this allows for interactions at long distances. Could someone here please rewrite it so that it is intelligible.
