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"This was possible to achieve thanks to state of art photon source and detection technology" What's a photon source thats not a lamp/laser?

alphydan 9y ago
I have not read the full article, but usually you need a laser which can produce single photons and which can control their polarisation (Other sources produce quantum superpositions of having 1 photon, 2 photons, 4 photons, etc. It's a probability distribution containing all those numbers).
deepnotderp 9y ago
You usually need single photon sources or SPDC.
- comstock 9y ago
  Don’t you need SPDC to get entangled photons anyway?
  - albutr 9y ago
    No, it's just one particular method of creating entangled pairs, e.g. there are integrated semiconductor devices that can be used to generate them using other physical effects (but AFAIK SPDC is what most people use in practical situations)
    - comstock 9y ago
      Interesting, do you have any search terms I could use to google for the semiconductor devices (I’ll try myself, but if you have a jumping off point that would be helpful).
      - albutr 9y ago
        Sure, one example that I'm familiar with is frequency entangled photons produced by parametric scattering of exciton-polaritons (it's scattering of quasiparticles in a quantum well which are strongly coupled to a photon field). Although, I actually can't recall if I've seen a convincing experimental demonstration of this. I have seen a bunch of experimental results which demonstrated entanglement using integrated silicon waveguides, where there are two waveguides that overlap in an effective "beam splitter" section then separate again (this is analogous to how you can get entanglement from an Hong-Ou-Mandel setup, which is two (EDIT: identical photons) incident on a 50/50 beam splitter which produces so-called "path entangled" photons). Here's a recent short review paper which goes over some additional semiconductor devices which can produce entangled photon pairs[1]. [1] https://arxiv.org/abs/1702.08823 https://arxiv.org/abs/1702.08823

alphydan 9y ago

I have not read the full article, but usually you need a laser which can produce single photons and which can control their polarisation (Other sources produce quantum superpositions of having 1 photon, 2 photons, 4 photons, etc. It's a probability distribution containing all those numbers).

deepnotderp 9y ago

You usually need single photon sources or SPDC.

comstock 9y ago
Don’t you need SPDC to get entangled photons anyway?
- albutr 9y ago
  No, it's just one particular method of creating entangled pairs, e.g. there are integrated semiconductor devices that can be used to generate them using other physical effects (but AFAIK SPDC is what most people use in practical situations)
  - comstock 9y ago
    Interesting, do you have any search terms I could use to google for the semiconductor devices (I’ll try myself, but if you have a jumping off point that would be helpful).
    - albutr 9y ago
      Sure, one example that I'm familiar with is frequency entangled photons produced by parametric scattering of exciton-polaritons (it's scattering of quasiparticles in a quantum well which are strongly coupled to a photon field). Although, I actually can't recall if I've seen a convincing experimental demonstration of this. I have seen a bunch of experimental results which demonstrated entanglement using integrated silicon waveguides, where there are two waveguides that overlap in an effective "beam splitter" section then separate again (this is analogous to how you can get entanglement from an Hong-Ou-Mandel setup, which is two (EDIT: identical photons) incident on a 50/50 beam splitter which produces so-called "path entangled" photons). Here's a recent short review paper which goes over some additional semiconductor devices which can produce entangled photon pairs[1]. [1] https://arxiv.org/abs/1702.08823 https://arxiv.org/abs/1702.08823