Quantum Entanglement, Dark Counts, Coincidence Detection

[mindwalker_i]

38. Sir, you've just saved me a LOT of pain

and money! In fact, I'm saving this text just in case DU blows up (not as far fetched as one would think).

The green LEDs are a really good idea too. At least at the beginning, I'll use IR filters, but hopefully, later I can enclose the interferometer and detectors in a box, with just a hole and tube to pipe in the entangled beam. Possibly by firewalling the pump beam, I can just get the IR photons and eliminate lossy filters and other components.

Both NewLight and Excelitas have e-mailed me back and answered most of my questions. I'll probably order the BBO soon, and in the meantime continue to build up the parts for the interferometer, as well as a switching mechanism to guild either the entangled beam or the alignment beam into the interferometer. This would be a good place to put a galvanometer, actually. Or two since I'll probably make a second interferometer for the other beam.

Another thing I want to do is stick a set of galvos on the outputs of the interferometer, then have them guide the outputs through lenses and to two (cheap, visible) detectors. The book I mentioned talked about these: TSL254R-LF. I picked up 10 or so from Digikey a while back and haven't used them yet. This would allow me to validate the setup with visible light, develop a circuit to read the light intensity for a grid of positions, and send that to Linux through USB. Converting it to do the same for the detectors shouldn't be that hard. The scanners could also direct the output beams either to that, or to the real detectors later, so I can just switch between visible and entangled light (and stick a cork in the detectors when doing the visible stuff).

I just rebuilt the optic holders, so now I need to build the plates to bolt onto the rotating tables. The two beam splitters will go on those so their angles can be easily adjusted. That would be something to motorize for the online experiment, although those are really expensive.

Anyway, I'm rambling because I'm excited (hey, maybe I'll emit a big, fat photon ), so I'll shut up. But again, thank you so much for the information!