Bell's circuit beginner's question: Sampling alters, - what's normal?

[ndvcxk123]

TL;DR

Sampling one of the two split photons results in probability alteration toward spin of entangled photon, ok, but how can normal outcome be determined w.o. sampling ?

Yes, I should hit the books more, so forgive the basic question. I take it normality is known by observing unsplit photon spin ? But how can one then exclude that split photons in themselves might have different probability outcomes ? Thx much in advance. (Please pardon that only moderately-talented people outside physics cannot quickly learn bra-ket notation...)

 

[vanhees71]

I've no clue what you are talking about. You should clearly describe your problem. Maybe you then even get a clue about the answer yourself!

 

[DrChinese]

Summary: Sampling one of the two split photons results in probability alteration toward spin of entangled photon, ok, but how can normal outcome be determined w.o. sampling ?

Yes, I should hit the books more, so forgive the basic question. I take it normality is known by observing unsplit photon spin ? But how can one then exclude that split photons in themselves might have different probability outcomes ? Thx much in advance. (Please pardon that only moderately-talented people outside physics cannot quickly learn bra-ket notation...)

Just to add to vanhees71's comment: you are using lingo that is not common, and therefore we can't understand your question.

Parametric down conversion (PDC or SPDC) can split a photon into a system of 2 entangled photons. We usually just talk about the system of 2 entangled photons rather than discussing how they became entangled (since there are a number of other ways to create entanglement). I am guessing you want to talk about entanglement, and not parametric down conversion (which is actually a completely different topic).

I don't know what you mean by "probability alteration" or "normal outcome without sampling" as these phrases are unique to you. Bell tests on entangled photon pairs produce statistical results which match the predictions of quantum mechanics (specifically the percentage of matches - HH or VV - relative to the angles the photons' polarization is measured). Phrases such as "normality" and "unsplit photon spin" are likewise unique to you.

If you could reformulate your questions in more common terminology, we could attempt to answer. You might try reading some existing PF threads to get a better idea of phrasing, or perhaps a few Wikipedia articles.