I had a What the Fudge moment like Planters when I watched this video. Then I remembered a former employer had sent me to a non-linear optics seminar for a week. I was there because we sponsored the seminar, not because I was expected to learn it. I ignored all Type I discussion at the seminar because all I cared about was Type II.
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She's vastly simplified the explanation, and left a lot out. Sadly she left out a few critical things.
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Type Two non-linearity can occur with six possible input photon states. Type One is far more selective, I think its only two or three input states for a 45' input. However the output when doing Type I sub-harmonic generation will decompose into the two output polarizations with a 50/50 probability, if the sub-harmonic phase matching input characteristics are met.
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The few incoming photons that meet the right conditions for type I non-linearity in a parametric oscillator are down converted, and exit at a specific walk-off angle. If she has an entangled pair, thus they co-incide on the detectors on the angled path. If she has a non-selected input photon, the Type One crystal does nothing, acts as a waveplate, and the photons are de-selected for detection and pass straight thru.
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Un-entangled, unconverted photons exit with one rotated polarization, and on axis with the input beam. Entangled photons exit at a specific angle and a 50/50 chance of either orthogonal polarization. They will co-incide on the two detectors at the same time, allowing for corellation detection.
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Two NLO crystals suggest there SHOULD be at least four possible selection exit paths for entangled photons. She's missing something in her talk.
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I barely understand this property for Type One, take my explanation with a grain of salt. I just use non-linear crystals for fun and profit. I hate the theory part.
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They paid a lot of money for a crystal house to pre-align this crystal pair for them. I'm guessing X-Ray orientation was used.
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Lets paint this for what it is. Scientist Dad is working very hard to place his Daughter on a specific, advanced, scientific career path. Good Quantum Mechanics people need about a half decade of study before they can clearly explain what they are working towards. She's not there yet.
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Steve
Last edited by mixedgas; 12-05-2015 at 11:54.
Qui habet Christos, habet Vitam!
I should have rented the space under my name for advertising.
When I still could have...