But, would One Photon Illuminate an Object enough in said room?
Don’t objects absorb and release photons, in their respective wave lengths?
Add in the equation One bar of gold and another of silver.
Would one photon be able to decipher one from the other, by color band?
Is a photon a carrier particle that can morph at will, depending on atoms it encounters, then changes wavelength the same way?
Stop making me think dammit…:dubious:
A very interesting question. When Gaboir invented holography the light source with the longest coherent length was a highly-filtered mercury arc, and even then the coherence length was , IIRC, sub-millimeter. Holograms were boring in those days, and for the next 14 years until Leith and Upatnieks used a long coherence length HeNe laser to make a hologram that looked 3D. Could you get the same effect by using single photons and really long exposure times, without all that troublesome filtering?
I don’t think so. Let’s say you’re trying to make a diffraction pattern of a double slit hologram like JacobSwan describes, only using a cheap mercury source. The problem is that the pattern has a wavelength dependence – the shorter the wavelength, the smaller the pattern. Coherence is related to the range of wavelengths you’ve got, and an unfiltered mercury source is still going to have a broader range of wavelengths than a laser. It’s true that each photon interferes with itself, but photons of different wavelength will try to make slightly different sized patterns. These are going to average out to a blurry pattern in the long run, rather than a sharp pattern made by a very narrow range of wavelengths. The net result of coherent interferences of different wavelength photons won’t be the same as large-scale interference of multiple single-wavelength photons.
Sorry. Nice idea, though. Worth an undergraduate experiment, like JS’s.
Thats why I said NARROW 
If it was monochromatic would it work ?
Ain’t no such thing as monochromatic – there’s only different degrees of narrow.
Yeah, it’d work. But if I’d narrowed by bandwidth down enough to the point where this would work, why bother making my hologram out of single photons? It’d go a lot faster with as many as I could hit the film/dichromated gelatine/whatever with.
another note:
even though your photon will always be correlated with itself, any source with a fjnite bandwidth will have a coherence length determined by that bandwidth. And you can’t make a hologram of an object bigger than your coherence length. again, each individual photon will giv you a good data point, but your collection of points from the range of photons will be decorrelated after you exceed the coherence length. So there’s no point in a hologram built out of single photon exposures, as far as I can see.
Yes…yes…yes
Why do it? First, cause its hard to do ?
Second, maybe you would like to make a nice 3D reflection hologram yet you dont have a laser. Is there a way to get a very narrow/nearly monocromatic light source that isnt a laser? If so, whats the coherence length? You are implying that the coherence length would HAVE to be extremely short. Not that you want it short, that these methods would result in short kengths.
As I say, Gabor in 1948 used a highly-filtered mercury arc with a single line because that was the highest intensity narrow-band source available to him. You can make narrower sources with higher output out of mercury emission lines – by building them into lasers. I’m not sure if any of the new technologies (like quantum dots) would give you a better bandwidth without making a laser
Okay slight hijack. I still don’t get it. Regardless of the Watts, one photon in a room at one time would have to hit something and then hit your eye. There doesn’t seem to be any way that I can imagine that one photon in a room at one time could carry enough information to see anything except one photon. Am I missing something fundamental?
You wouldn’t see an image from a single photon, just (roughly) a single pixel. But if you get one photon, and then another, and then another, one after another really quickly, you could see an image from that.
Okay, that makes sense. But you would have to assume that the photons are hitting enough areas on a page to read it. Or does the speed of the photons take care of this problem? (i.e. there are so many in such a short amount of time that one can expect the entire page to be completely covered very quickly)
I know that Wikipedia says that a rod cell can be sensitive to a single photon, with no citation provided, but I have a hard time believing that. For instance, even humans emit visible light up to 100 photons per cm2 (ultra-weak light emission/human biophoton emission) and I’ve never seen a glowing person before even in the darkest of settings.
Well, unless the object is luminescent or incandescent it will only reflect, absorb, or transmit visible light. The emission will, with few exceptions like Anti-Stokes fluorescence, be in the longer wavelength of the infrared band.
It would depend on the reflectance of each material at the wavelength of the incident light. An example of this is any sort of colored light bulb, for example a red light - it tends to make everything appear red because there is no other color to reflect, so even if you have, say, a green object and a brown object they will look more or less the same.
(bolding mine) Say what? Are we talking about the upper tail of the emission curve here?
Were you in a place with less than 100 photons per cm[sup]2[/sup] emission otherwise? The human would have to be the brightest light source.
Is there a minimum photon energy needed for our eyes to receive?
Not sure what emission curve you’re talking about. This is a form of luminescence, not incandescence.
http://en.wikipedia.org/wiki/Biophoton
I’m at home so I don’t have the journal articles, but I know that one estimated 100 photons per cm2 and I think one stated that it was something like a thousand times less than a human eye could perceive. This is in the visible range, IIRC something like 480-640 nm is the range for one mechanism for biophoton emission. I’ve been in some very deep caves before where I assume there weren’t any light sources (after headlamps and flashlights were turned off), and everything was absolutely pitch black. I don’t think photon energy really has anything to do with it since the energy is only a function of wavelength (E=h*c/lambda), so a red photon at 650 nm will be the same regardless of what emitted it.
Maybe you were talking to Richard Feynman’s cat?
100 photons per cm^2 per what time? Is that per second, per lifetime, what?
There should have been a per second in there.
For a flight path of 2 feet, one photon at a time means about 500 million photons per second. The human eye needs to receive photons at about 50-100 per second to trigger a response, or so I’ve heard (not-much-of-a-cite). So you could paint the retina with a 5 megapixel image (better than a Kindle!), one photon at a time, from a scanning laser source a couple feet away. From across the room you’d lose some resolution but could probably get a readable large-print page.
If my BOTE calculations are right, a star like the Sun, 4 lightyears distant, would emit about 5E-11 watts onto a human retina, so this number isn’t really all that absurd.