Questions tagged [non-locality]
The non-locality tag has no usage guidance.
62
questions with no upvoted or accepted answers
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A Venn diagram for: (non-)locality, (non-)realism, (non-)contextuality, (non-)signalling, (dis-)entanglement
I recently asked a (yet-unanswered) question about the relationship between state-dependence and violations of realism. The more I read on the subject, the more I find myself digging deeper in a ...
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Justification for the derivative expansion in the Exact Renormalization Group
In the Exact Renormalization Group formalism, specifically the formalism of Wetterich, one writes down an evolution equation for the effective average action $\Gamma_k[\varphi]$, see f.ex
$$
\...
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What does it mean for an extended operator to possess "local excitations"?
In the context of defect conformal field theory, we consider in operator product expansions "local excitations" of the defect (see e.g. text between eq. $(1.1)$ and $(1.2)$ in the paper ...
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How are contextuality and locality related?
I know how quantum non-locality is defined in Wikipedia
quantum nonlocality is a characteristic of some measurements made at a microscopic level that contradict the assumptions of local realism ...
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Decomposition of rank-2 field and local interactions
Any rank-2 tensor can be decomposed in the following way
$$
\phi_{\mu\nu} =\phi_{\mu\nu}^{TT} + \partial_{(\mu}\xi_{\nu)} +\frac{1}{4}T_{\mu\nu}s+\frac{1}{4}L_{\mu\nu}(w-3s)
$$
where $\phi_{\mu\nu}^{...
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Are all instances of quantum non-locality problem artifacts of the use of classical concepts in quantum physics?
Consider experiments involving entangled spins, say two-spin 1/2 particles in the singlet state:
$$\left|\psi\right> =\frac{1}{\sqrt{2}}\left[\left|\uparrow\downarrow\right> - \left|\downarrow\...
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Difference between PR correlations and entanglement correlations?
(As pointed out by helpful users, one of the bolded claims is interpretation dependent. Therefore, unless otherwise specified, Copenhagen interpretation is used throughout)
Recall that for classical ...
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Pseudo-randomness of observables
There is a somewhat recent paper by Colbeck and Renner that, given the assumptions — 1) QM accurately predicts the correct statistical results in experiment (which so far has always been found to be ...
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Can a point in the quantum set of correlations violate more than one independent facet Bell inequality?
Usually, depictions of the quantum set of correlations and the local polytope look something like:
In this image it looks like non-local points belonging to the quantum set (in yellow) violate only ...
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How can two phonons be entangled when the atoms in the crystal are not?
It is my understanding that you can use phonons to make a gaussian packet, which would behave like a quantum particle. I also believe that you can make two such packets and entangle them, that is ...
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How localized are photons in a quantum field?
Are photons or other quanta at least somewhat localized in a quantum field?
My limited understanding of quantum field theory is that photons or other fundamental particles (quanta) are excitations of ...
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Measurement of the spin of the EPR pair in two orthogonal directions and how did Einstein tackle this?
Let us consider two types of measurement in the EPR experiment. In Bohm's description of this experiment, the state of the electron-positron (called the EPR pair) is given by
$$
|{\rm EPR} \rangle =\...
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Are violations of realism the same thing as contextuality?
I am basically looking for a counter-example where we'd get contextuality but not violations of realism (and vice-versa). If no such counter-examples exist, then it seems to me that they're really one ...
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Is it possible to use Quantum Monte Carlo for non local interactions?
I just have a brief question about QMC being applied to calculating expectation values. If I were to calculate the expectation value of an operator, like the energy via a Quantum Mote Carlo ...
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Does a pilot-wave theory need to be stochastic in a discrete space-time?
I have found an article about Bohmian mechanics on a lattice with discrete space and time, the link of which is given below:
https://arxiv.org/abs/1606.02883
Here the motion of quantum particles is ...
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