Dissecting entanglement

[zonde]

Speaking about entanglement I find it helpful to look at experiments.
In particular I like this one, even so it's far from more sophisticated experiments that are using state of the art equipment. That's because it goes into more basic details about entanglement experiment.
https://arxiv.org/abs/quant-ph/0205171
In particular for me equation (6) gives helpful insights:
$$|\psi_{DC}\rangle = \cos\theta_{l}|H\rangle_{s}|H\rangle_{i}+\exp[i\phi]\sin\theta_{l}|V\rangle_{s}|V\rangle_{i}$$
Given that φ in the experiment can be smoothly adjusted in a quite straight forward way, that way one can experimentally change the state continuously between fully entangled state and completely "classical" product state.
For me it hints that entaglement can be dissected into local parts and a non-local part - a phase factor φ.

Is it just me or anybody else see this as insightful?

 

[anuttarasammyak]

Given that φ in the experiment can be smoothly adjusted in a quite straight forward way, that way one can experimentally change the state continuously between fully entangled state and completely "classical" product state. For me it hints that entaglement can be dissected into local parts and a non-local part - a phase factor φ.

I have not read the paper. I just see your equation. It represents a rotation about the z-axis on the Bloch sphere, and every value of ϕ corresponds to a valid quantum state. The parameter ϕ is simply the relative phase between the first and second terms of the state vector, and it has nothing to do with the distinction between local and nonlocal properties.

 

[zonde]

I have not read the paper. I just see your equation. It represents a rotation about the z-axis on the Bloch sphere, and every value of ϕ corresponds to a valid quantum state. The parameter ϕ is simply the relative phase between the first and second terms of the state vector, and it has nothing to do with the distinction between local and nonlocal properties.

Oh, but look at the paper. ϕ represents tilt of a quartz plate in pump beam that does not lead to any locally observable changes in either of the two arms of the experiment. While changes in other terms in contrast lead to observable consequences in local statistics.