All Questions
Tagged with locality quantum-information
17
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How is information defined when considering locality in quantum mechanics?
$\newcommand{\ket}[1]{|#1\rangle}$
My question is a follow-up from this discussion about the presence of non-local correlations in a theory that is deemed local. The first answer talks about the ...
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Is there any restriction for locally mapping a given 2-qubit density matrix into a desired 2-qubit density matrix with lower entanglement?
Suppose we're given a 2-qubit density matrix($\rho_{4\times4}$). we can apply two local maps on each of these qubits seperatly. So the output is density matrix($\rho^{\prime}_{4\times4}$).
I'm ...
- 27
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Equivalence of two entangling operators with respect to local operators
Suppose that $U_1$ and $U_2$ are two (entangling) operators that act on a quantum system consisting of several qubits. Is there any criterion to tell if these two are equivalent up to applying ...
2
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Non- Local operators and Entanglement
Given a separable state, $|\psi\rangle$ = $|a\rangle\otimes|b\rangle$, operating on this state with a local operator of the form, $A\otimes B$ will not lead to an entangled state. Is the converse true?...
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What are the implications of rejecting the local tomography assumption?
Recently I presented on the paper by Renou, et. al. in Nature (Quantum theory based on real numbers can be experimentally falsified) developing an experimental technique for rejecting real ...
- 13
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On the Bell's Theorem / Bell-type Inequalities and the Kochen-Specker Theorem
It appears to me that the Kochen-Specker theorem, if not Gleason’s theorem already, seals the fate of realism / value definiteness (with possibly the additional assumption of non-contextuality, ...
- 173
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Are all physically realistic Hamiltonians local?
My understanding of modern physics is that physicists think that, fundamentally, physical laws are local. For system A to interact with system B, they either need to be very close to each other or ...
- 1,327
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Replication of Single Particle QM with Local Hidden Variables
In learning device-independent QM from [https://arxiv.org/abs/1303.3081], Scarani tells us that all quantum statistics involving one particle can be reproduced with local (hidden) variables. He then ...
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Difference between an entangled pair of photon and two magnets in a box? [duplicate]
I try to understand quantum entanglement and especially what it’s called « Action at a distance »
from my understanding, if you have a pair of entangled photon, after measuring the polarization of ...
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28
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How do we know quantum entanglement works no matter the distance?
It is said quantum entanglement works regardless of distance. 2 particles can be entangled and information is shared instantaneously, even if they are lightyears away from each other.
But how do we ...
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How exactly does the proof of Bell's theorem fail if you remove the locality assumption?
In this paper Bell derives his famous inequality using the assumtions of locality and realism. In order to understand how the locality assumption affects the derivation of the inequality, and why it ...
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Why do we only time-evolve one operator in the Lieb-Robinson bound?
Background
The Lieb-Robinson bound is said to provide some notion of causality in non-relativistic quantum systems with bounded local interactions. Formally, it can be stated as follows.
Theorem (...
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11
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Where is locality used in CHSH/Bell's inequality?
A very similar question is asked here, but I'm still confused :(
From Bell, in a hidden variable model, $A = A(\lambda, a)=\pm 1$ is the observed spin of the first particle around axis $a$, and $B = ...
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Product of Local Hamiltonians is Local
Let $H_1,H_2$ be local Hamiltonians (i.e. interactions are finite range). Let us form the product of the exponentials of both. By Baker-Campbell-Hausdorff, this defines a third Hamiltonian,
$$e^{H_1}...
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Is there something wrong with Bell's inequality? [closed]
Repeating the title because that's what I posted on Reddit and didn't get an answer. But I guess the proper question is: is there something wrong with the experiment? The text over on Reddit:
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