One Photon In, TWO Photons Out 

Bravo, Ryan! How are you doing lately?

You prolly dont care but does someone know of a method to log back into an instagram account? I was stupid lost my account password. I appreciate any help you can give me!

@Carmelo Benicio instablaster :)

@Kenzo Markus i really appreciate your reply. I found the site thru google and Im trying it out atm. I see it takes a while so I will reply here later when my account password hopefully is recovered.

@Kenzo Markus It did the trick and I finally got access to my account again. I'm so happy! Thank you so much you really help me out :D

@Carmelo Benicio glad I could help xD

It isn't and technically the process is not even possible because of angular momentum conservation. It's one photon in, something happening to the bulk of the conversion crystal and then two photons out. That "something" is the hard part.

Isn’t it essentially similar to crystalline structures and it’s similar to complex mirrors reflecting light?

photon hits the atoms of the material and is absorbed, the material then reacts to that by emitting two lower energy photons.

michrowave the proton the blue one

It's purposefully obtuse. Keeps people in a job if it's made excessively complex.

Great question, I'd love to hear the answer to this.

Yes!

Good question. If you put one photon-counting detector in the transmitted path and another detector in the reflected path, you will have your answer. A single photon can only be detected in one of the two detectors. That is, it can only completely reflect or be completely transmitted. That is what it means for the photon to be a single particle. If the reflectance of the surface is, say 4 % (that is something you can measure classically), then 4 % of the time the detector in the reflected path will click and 96 % of the time the transmitted path detector will click. Each time you do the experiment with a single photon input there is no way of knowing which outcome will happen. You only know the probabilities.

@@alanmigdall8697 Thank you very much. That was my best educated guess, but it was only a guess. You've now revealed a 2nd excellent reality experiment with physically logical explanations. Many other people like myself have been searching the internet unsuccessfully for the important results of that reality experiment. You might consider demonstrating and explaining that experiment yourself on RU-vid. Many people could benefit from it, especially if your title and keywords make it easy for people to find the video. I might suggest a title and/or keywords including "single photon refraction reflection". If you are not interested in making such a video, perhaps you know a colleague who might be? I notice a comment here by natalie1111111able Potter, who enquires if you have a video detailing how the detectors in double slit experiments work. I am also very curious about this. If such a video has not already been made, I personally would prefer you to be the 1 to make it, as I very much appreciate your physically logical explanations. Regarding your own experiment you've demonstrated and explained here, it's helpful to me to learn how energy and momentum are conserved in photon-photon interactions. I've invented a unifying physics theory, matter theory. I have 8 videos on RU-vid promoting it for funding. If I can possibly help you, please contact me.

To Alan Migdall: I am curious again about your own reality experiment. In parametric down conversion, what exactly causes 1 photon to split into 2 photons conserving momentum and energy? And, can your experiment be done in reverse, parametrically up converting 2 photons into 1 photon?

@@joshuahong4921 I don't know what it might be called.

No. The efficiency of the conversion process is on the order of parts in a million and the energy of the output photons is wrong and can't lead to a second split in the same crystal.

@@schmetterling4477 Thank you.

Any discrete measurement of a wave can look like a particle, or a quantized unit. This does not mean the photon changes. It was and always is a packet of electromagnetic energy.

There are no particles. Photons are field energy.

@@lepidoptera9337 Even if I accept that, how can they then be quantified?

@@numbynumb Energy is actually not quantized (it is observer dependent, just like in classical physics. hence we get doppler shift for photons just as well as for classical waves). Angular momentum and spin are quantized. It just happens that energy, momentum and angular momentum/spin are joint at the hip by special relativity, so whenever systems change their angular momentum by a discrete step, they also have to change their energy by a step.

​@@lepidoptera9337I think some energy like photons can be quanitzed. Otherwise he would only be assuming that the output are two equal halves of the energy instead of an unknown output from the material lattice

@@patrickday4206 Quantization means that a physical property can only come in the exact same amounts (or multiples thereof), like in case of angular momentum or charge (all spins and all electrical charges are exactly the same for all we know). Energy can come in any amount. It's not quantized. A photon is a discrete amount of energy, but its energy is not what is quantized. Only its angular momentum is.

That's just an efficiency question. One can probably make much more efficient converters and eventually somebody will.

Then you get a point deduction in your test for not understanding angular momentum conservation.

Some people have suggested that light may travel in a helix two entangled could collapse into one partical correct?

It's not a mystery. The only mystery is why people don't want to understand that photons are changes in energy and not objects. :-)

We are teaching in high school that "the photon" is the amount of energy detected by the detector. A photon is not some "thing" that has energy. It IS the energy that gets irreversibly absorbed from the electromagnetic field by the matter of the detector. I still can't get my head around how hard it must be for people to differentia the meaning between "something being" and "something having" in the English language. ;-)

That is correct. Conservation laws require that something else is happening. That's what we need the conversion crystal for... to account for the momentum and angular momentum balance.

I don't know how that experiment is supposed to "prove" photons... since the non-linear optical crystal can certainly "split" a photon in two. Not to mention that photon number is not conserved under any circumstance, neither in low energy (emission, absorption, thermal radiation) or high energy physics. That the photon number is (almost) constant on a beam splitter is a special property of the beam splitter. It proves nothing particular about the electromagnetic field. :-)

@@schmetterling4477 The proof wasn't on properties of the photon, it just set up an experiment where the only possible scientific explanation for the outcome is the photon. As far as I am aware other experiments that between Einstein's 1905 proposal of the photon and Grangier's 1985 experiment could only tangentially prove the photon. Our experiment was recreating the 1985 experiment consistently with comparatively inexpensive equipment (>15,000$). The book we used for reference was "Quantum Mechanics: Theory and Experiment" by Mark Beck. We used different equipment, we added an experiment to test the sensitivity of our equipment and did experiments 1&2 as well as parts of 3&4.

@@loganreidy7055 That "other experiments don't prove field quantization" is absolute nonsense. The best proof we have for field quantization is the stability of matter. Classical theories can not account for that.