« on: 27/06/2023 17:40:27 »
I will give a basic example of what I mean.Quote from: OPHow do we know that particles are entangled?Requirements include:
- they came from the same entanglement "factory", ie
- they have a shared history,
- and a shared quantum state.
- so their state is correlated
Some quantum "factories" are very inefficient; for example, the parametric down-converter method has just 1 photon in millions entangled. Much better methods of entanglement are needed for a workable quantum computer - typically these involve electromagnetic fields operating on electrons.
https://en.wikipedia.org/wiki/Spontaneous_parametric_down-conversion#ExampleQuote from: Zer0Can entangled electrons have an identical spin Sometimes?In the Spontaneous parametric down-conversion example provided above, Wikipedia lists two crystals with different chemistries - one generates entangled photons with parallel spins; another crystal generates entangled photons with opposite spins.
Or do they have to or must have opposite spins Always?
- But the dominant non-entangled photons are not correlated.
I know that they will entangle 2 electrons for example. Then they separate them. When they observe the spin of one electron, they instantly know the spin of the other. How do they know that the spins of each electron were not predetermined when they were entangled.
This is a very common question from people like me that do not know a lot about the details of entanglement. They do have an answer to this question, but I can never understand it.