Slit experiments - how do they emit a "single photon?"

[Magic_Man]

I've read about the famous double-slit experiments many times. I generally hear first that a "beam of light" is directed at the slits, resulting in the dark/light interference pattern. Then, "one photon at a time" is fired at the slit, and voila, the same interference pattern. I've never understood how they do this; if light is both particle-like and wave-like, how can they isolate a single particle?

~MagicMan

[thylacine]

[ QUOTE ]
I've read about the famous double-slit experiments many times. I generally hear first that a "beam of light" is directed at the slits, resulting in the dark/light interference pattern. Then, "one photon at a time" is fired at the slit, and voila, the same interference pattern. I've never understood how they do this; if light is both particle-like and wave-like, how can they isolate a single particle?

~MagicMan

[/ QUOTE ]

I'm just guessing, but I guess they just put a really strong filter in front of their light source to cut it down to, say, one photon per second. They can easily calculate the rate, but they have no control over when photons are emitted. They would just be emitted randomly at a rate of about one photon per second.

[arahant]

There are a bunch of ways. One is to trap an ion between two mirrors, and then excite it with a laser. Just google 'single photon'

If your question is, 'how can a wave correspond to a single photon'...the total energy of the wave is equivelent to the energy of a single photon.

Edit...i think the above poster alluded to this...
The initial experiments (the ones you read about) aren't actually a single photon...the are a series of photons, emitted at a relatively slow rate (such that we know they don't interact). It is fairly recent that we could actually control the emission of a single photon reliably...

[Skidoo]

Wavelength is inversely proportional to energy per photon. You can call a lab supplier for a cheap gizmo that will reliably generate photons of a convenient wavelength for your slit size. That's easy enough. Then lower the power output so that only one photon per a sufficiently long time accounts for all the energy used. Make sure the photons don't commingle in transit. Post pictures. Good luck.