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boffinwannabe

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- Thread starter boffinwannabe
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boffinwannabe

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- #2

alexepascual

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I think you should be able to find plenty of threads in this forum where things like the EPR experiment, causality, realism, non-locality etc. are discussed.

With respec to the title of your post, I think it is somewhat confusing. Before reading the post, I thought you would ask about the speed at which entanglement is generated. Entanglement is assumed to exist from the time the particles interacted, were generated or got correlated through some other mechanism. What you are asking is about the measurement events.

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boffinwannabe

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- #4

DrChinese

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Frame of reference has nothing to do with the speed of entanglement decoherence. There is no measurable "difference" present in the effect. Please recall that there is nothing obviously different after collapse related to one particle alone. You have to look at the entire system together.

- #5

bohm2

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According to this paper, the hidden/private quantum signals that exist between entangled particles/systems cannot remain hidden if the speed of these "private lines" is anything less than infinite velocity/instantaneous.

**Quantum nonlocality based on finite-speed causal influences leads to superluminal signaling**

http://arxiv.org/pdf/1110.3795v1.pdf

**Quantum non-locality based on finite-speed causal influences leads to superluminal signalling**

http://www.nature.com/nphys/journal/v8/n12/full/nphys2460.html

**Looking Beyond Space and Time to Cope With Quantum Theory**

http://www.sciencedaily.com/releases/2012/10/121028142217.htm

One of the authors (Gisin) discusses other ramifications in a follow-up piece recently posted in arxiv:

**Quantum correlations in Newtonian space and time: arbitrarily fast communication or nonlocality**

http://lanl.arxiv.org/pdf/1210.7308.pdf

Perimeter lecture from the lead author:

**Quantum Nonlocality Based on Finite-speed Causal Influences Leads to Superluminal Signalling**

http://pirsa.org/displayFlash.php?id=11110145

The new hidden influence inequality shows that the get-out won't work when it comes to quantum predictions. To derive their inequality, which sets up a measurement of entanglement between four particles, the researchers considered what behaviours are possible for four particles that are connected by influences that stay hidden and that travel at some arbitrary finite speed. Mathematically (and mind-bogglingly), these constraints define an 80-dimensional object. The testable hidden influence inequality is the boundary of the shadow this 80-dimensional shape casts in 44 dimensions. The researchers showed that quantum predictions can lie outside this boundary, which means they are going against one of the assumptions. Outside the boundary, either the influences can't stay hidden, or they must have infinite speed.

http://arxiv.org/pdf/1110.3795v1.pdf

http://www.nature.com/nphys/journal/v8/n12/full/nphys2460.html

http://www.sciencedaily.com/releases/2012/10/121028142217.htm

One of the authors (Gisin) discusses other ramifications in a follow-up piece recently posted in arxiv:

http://lanl.arxiv.org/pdf/1210.7308.pdf

Perimeter lecture from the lead author:

The experimental violation of Bell inequalities using spacelike separated measurements precludes the explanation of quantum correlations through causal influences propagating at subluminal speed. Yet, it is always possible, in principle, to explain such experimental violations through models based on hidden influences propagating at a finite speed v>c, provided v is large enough. Here, we show that for any finite speed v>c, such models predict correlations that can be exploited for faster-than-light communication. This superluminal communication does not require access to any hidden physical quantities, but only the manipulation of measurement devices at the level of our present-day description of quantum experiments. Hence, assuming the impossibility of using quantum non-locality for superluminal communication, we exclude any possible explanation of quantum correlations in term of finite-speed influences.

http://pirsa.org/displayFlash.php?id=11110145

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