Entanglement might be the result of an underlying law?

[Roberto Pavani]

I was just highlighting a passage from the paper linked by @bhobba. My understanding is that in the Heisenberg picture, the operators carry all the dynamics locally (each qubit's descriptor evolves based only on local interactions), while the state vector is fixed, so the "nonlocal update" that seems to happen at measurement in the Schrödinger picture doesn't appear.
The locality claim is developed in sections 2–7 of the paper.

Regarding the interaction picture: good question, I'd guess it inherits a mix of both features, but I don't know.
Perhaps @bhobba has a clearer view on this.

 

[PeterDonis]

I cannot discern where they show that Heisenberg picture is local in this paper.

They define "local" to allow for the possibility of "locally inaccessible information", which is what many people would just call "nonlocal"--the information contained in Bell inequality violating correlations between entangled particles, which can't be extracted until all of the measurement results on all the particles are collected in one place and analyzed.

So I would say the issue here is what meaning is to be given to the term "nonlocal". The paper adopts a very restrictive meaning, where basically the no signaling theorem would have to be violated for them to consider a theory "nonlocal". So of course QM is not "nonlocal" by this definition. But none of this makes the weirdness associated with Bell inequality violations go away.

Would then interaction picture be local and non local at the same time?

The paper's answer would be no, since the answer they give to the question quoted in post #26 is no. In other words, they say the "nonlocality" in the Schrodinger picture is only apparent, and QM actually is local. But again, this is because they're using a definition of "local" that many people would not say is suitable for that word.

 

[Matterwave]

So I would say the issue here is what meaning is to be given to the term "nonlocal". The paper adopts a very restrictive meaning, where basically the no signaling theorem would have to be violated for them to consider a theory "nonlocal". So of course QM is not "nonlocal" by this definition. But none of this makes the weirdness associated with Bell inequality violations go away.

I only very briefly glanced through the paper and the no-signalling theorem also quickly came to mind (maybe because they keep talking about information exchange as part of their definitions). But it was only a feeling and I have not read the paper in detail enough to make any judgement.

 

[olgerm]

Agreed. And more generally by Dirac's equation for relativistic particles. The entanglement is already in the formalism, no extra axiom needed.
Though I suspect the OP's real question may be whether entanglement hints at something deeper beneath Schrödinger/Dirac, but that's OT here.

in QM electron is point-particle. In QFT(after EW-symmetry breaking) electron is massive spinor-field. in QFT(before EW-symmentry-breaking) electron is described by 2 different massless spinor-fields.
There may be many formalisms and ways to calculate time-evolution of wavefunction(including dirac equation in some models), but I think schrödinger-equation (it is also called schrödinger functional in QFT) works in both QM and QFT. Dirac equation can be derived from it if corresponding Hamiltonian is put into it.
schrödinger-equation: $\frac{d\Psi}{dt}=-i(2\pi)H(\Psi)$
using units where h=1. (planckonstant=1)
Just in QM argument of $\Psi$ is time and coordinates of particles(that are modeled as point-particles), but in QFT argument of $\Psi$ is time and field-configuration. In QM hamiltonian is derived from Coulombs law, but in QFT Hamiltonian is function of field-configuration.