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Questions tagged [epr-experiment]

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Reality, locality, and universality in the EPR paradox

Apologies if this has been asked before. I did some searching but didn't see it anywhere asked quite like this. Thanks in advance for any insights. Caveat: I am an organic chemist and thus ...
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2answers
90 views

Better Entanglement Explanation Required [duplicate]

It seems to me I have not read or understood a better explanation for quantum entanglement than Einstein's left and right glove explanation. If some Aspect (pun intended) of an entangled quantum ...
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0answers
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How to find a CSCO (Complete Set of Commuting Operators/Observables) of an eigenfunction?

So, say you have an eigenfunction defined as: $\psi \left(x_1,x_2\right)=\int _{-\infty }^{+\infty }\:e^{p\left(\frac{2\pi i}{h}\right)\left(x_1-x_2+x_o\right)}dp$ (The spinless 2 particle system ...
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2answers
82 views

Is the spin in quantum entanglement set at the moment the particles are separated, instead of when measured? [closed]

Is the spin in quantum entanglement set the moment the particles are separated, instead of transmitted instantaneously to its twin particle at the time of measurement? Wouldn't this make more sense ...
2
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1answer
92 views

The non-locality of Quantum Mechanics

I often heard physicists mentioning the EPR paradox or the quantum entanglement when talking about the non-locality of quantum mechanics, but wasn't quantum mechanics already non-local from the ...
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1answer
25 views

question regarding wikipedia page on pulsed electron paramagnetic resonance

Here, under the subtitle 'principle,' it describes what happens when you have a static magnetic field along the z axis, $ B_0 \hat{z}$ and microwave field parallel to the $x$ axis, $ B_1 \hat{x}$. I ...
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3answers
114 views

Quantum entanglement, how do we know there was no spin? [duplicate]

Im not a scientist, so go easy on the explanation! As I understand it we can create two entangled particles. The entangled particles have a spin property which is opposing. When we measure one of the ...
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0answers
31 views

Is local realism an inaccurate description of the Universe? [duplicate]

Has the big Bell tests proven local realism wrong? References: The Big Bell Test: Global physics experiment challenges Einstein Crowdsourced quantum reality-check gets crowdsourced peer review
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1answer
52 views

When does the wave function collapse in the EPR paradox experiment? Shouldn't this depend on the reference frame?

Suppose you have two entangled particles. Particle A, and Particle B. If the spin of particle A is up, then the spin of particle B must be down and vice versa. Now suppose you measure the spin of A ...
2
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1answer
63 views

Distinguish Definitions: Realism Scientific, Realism, and realistic

I was readying about study about bell's theorem, where I had the question about some definitions. Here's some of my summaries: Scientific Realism: (https://en.wikipedia.org/wiki/Scientific_realism#...
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0answers
108 views

How are joint measurements of quantum states realized experimentally?

I have a question regarding the experimental implementation of joint measurements of quantum states. While I understand for example the teleportation protocol using Bell states, something that still ...
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0answers
41 views

What's the invariance quantity under EPR and Bell's inequality?

I was reading and writing a study report about EPR and Bell's inequality. As the hidden variable and local realism was proven to be "false", and from many posts in physics exchange websites such as ...
3
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1answer
101 views

Are properties such as locality and realism properties of all theories, some theories, or interpretations of theories?

I have a strong intuitive feeling, based for example on the Bothe-Geiger experiment, that quantum mechanics is nonlocal. But intelligent people who have thought about these things make claims such as ...
2
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1answer
156 views

From locality to deterministic hidden variables

According to this link here Bell said: "My own first paper on this subject ... starts with a summary of the EPR argument from locality to deterministic hidden variables. But the commentators have ...
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0answers
37 views

EPR experiment with photons

In textbooks, the EPR problem and Bell's Inequality are dealt with for particles. However, when it comes to experimental verification, photons are used. The formula for the expectation value for ...
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1answer
158 views

Completeness of quantum mechanics and the EPR paradox

I am reading through the EPR paper and follow most of it. The authors argue that either QM must be incomplete (let's call this statement A), or incompatible observables can not have simultaneous ...
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2answers
82 views

EPR-Bohm paradox and Robertson uncertainty relation [closed]

Consider Bohm's version of the EPR paradox, where spin-1/2 are used. The bipartite system is in the state $$ \vert \Psi\rangle = \dfrac{1}{\sqrt{2}} \left( \vert \uparrow_x \rangle_A \vert \...
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0answers
51 views

What confidence level and margin of error are implicit in the statement the probabilistic predictions of quantum mechanics have been firmly confirmed?

This can be formulated as a problem of hypothesis testing, or sampling, in a statistical framework. For a confidence level of 0.95, and an error not exceeding 0.005, you would need a sample size ...
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0answers
86 views

Is there any basis in stating there are different levels of 'locality' or 'reality', within physics or physical theories?

EPR’s reality criterion and quantum realism has this paragraph (the paper has 0 citations, and I'm personally happy to call this metaphysics, but still!): A popular interpretation of Bell’s theorem ...
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3answers
147 views

Is it possible to know the efficiency of a particle detector without assuming the truth of Theory (e.g.,, Quantum Theory)

I reorganized the question to clarify exactly what it is that I'm asking. Suppose an experiment is performed where a particle detector records 50 particles per second, on average. Absent any other ...
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0answers
37 views

Could a degree of freedom mismatch between quantum and macro space explain EPR test results?

String theory tells us that there may be 10 or 11 dimensions, several of which are twisted around at a very small scale so that we cannot measure them. Could the statistical results from experiments ...
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1answer
37 views

How to understand the claim that ''positions'' of entangled particles are correlated? [closed]

Are both particles detected in the exact same spot of the detector? Something else?
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0answers
48 views

Understanding the classical expectation side of EPR/Bell inequalities

I like building educational models[1], and I’m collecting ideas for a quantum physics based one. I’m wanting to make sure I’ve got my head around the classical side of the Bell inequalities, ...
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1answer
274 views

Bell's theorem and how it solves the EPR paradox

Could someone explain to me how Bell's theorem solves the EPR paradox and 'spooky action at a distance'? From what I understand, when measuring a state, say spin up in the x direction, the wave ...
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1answer
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Since photons do not experience time (nor distance in that case), why did Einstein think it was “spooky action at a distance”? [closed]

A photon travels at c, so it experiences no time or distance. I imagine from the photon's perspective, it's rather just like a simple dot on some kind of 4D manifold. So it begs the question of why ...
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1answer
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QM explanation on entanglement for spin and the original EPR experiment

I have read this: http://en.wikipedia.org/wiki/EPR_paradox#Mathematical_formulation and this: How does non-commutativity lead to uncertainty? But it does not give me a specific explanation on the ...
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2answers
321 views

Quantum field theory version of EPR paradox

I've always been wondered that people speaking of EPR paradox formulate it only in terms of non-relativistic quantum mechanics and not quantum field theory which being a relativist generalisation of ...
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1answer
77 views

What causes the universe to manifest a given value upon measurement in super-deterministic theory? [closed]

Bell's inequalities show that we have to give up freedom or local realism. If we give up freedom, we have super-determinism, if we give up local realism, we have free-will. In super-deterministic ...
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3answers
238 views

Shouldn't local realism imply the superdeterminism?

I see that Bell has ruled out Einstein's local realism but not supredeterminism. I see that Bell has confessed that superdeterminism kills his inequality. You cannot apply Bell's inequality if ...
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0answers
43 views

Hidden character in EPR paradox [duplicate]

I am a beginner in Quantum Mechanics so i am pretty new to the EPR paradox although i have heard about it a long time ago but finally studying in detail. And came across a doubt: Why the hidden ...
2
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2answers
195 views

How is locality preserved in quantum mechanics?

I was reading this post: http://motls.blogspot.com/2015/06/locality-nonlocality-and-anti-quantum.html Specifically here: "There is no nonlocality. There is no action at a distance. There is no doubt ...
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2answers
871 views

Has Jaynes' argument for quantum mechanics as a possible theory of inference been debunked?

To my understanding, there is currently no scientific consensus on which interpretation of quantum physics is the correct one, if any. The most famous one, perhaps for historical reasons, is the ...
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3answers
2k views

Has Jaynes's argument against Bell's theorem been debunked?

As a student of theoretical physics I'm well acquainted with the multitude of crackpot ideas attempting to circumvent Bell's theorem regarding local hidden variable theories in quantum physics. ...
0
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1answer
137 views

EPR experiment with identical particles

This question is an extension of a question I asked earlier about the possibility of measuring the energy of just one particle in a system of many identical particles, which can be found here. One ...
4
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0answers
92 views

How long does it take to a local perturbation to propagate along a quantum system?

Imagine to have a one-dimensional system in its ground state, and to apply a local perturbation at one edge of the system. How does the system evolve after being perturbed? More specifically, how ...
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0answers
76 views

Schrodinger cat,another explanation of the phenomena

Much was written about Schrodinger's cat. But I still do not understand one point (may be the crucial one): is it possible that the cat IS actually in ONE state,dead or alive, but as nobody knows ...
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2answers
143 views

Why can't be the EPR experiment simplified?

Alice measures the spin of her electron on the x axis. She now knows the spin value of Bob's electron on the x axis at time T0. Bob measures the spin of his electron on the z axis. He now knows the ...
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3answers
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Does the following experiment disprove the Copenhagen interpretation?

I have a question concerning the scientific experiment proposed in the following video, (25:00-29:00) titled the "EPR Thought Experiment", which bears resemblance to the quantum eraser experiment. ...
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3answers
313 views

Does a magnetic field disentangle an EPR pair?

The spins of the both electrons of an EPR pair are undetermined before one conducts a measurement on one of them. Does a magnetic field determine (set up or down) the spin of one partner of an EPR ...
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2answers
648 views

Does the many worlds interpretation eliminate the spooky action at a distance paradox? [closed]

I'm sorry if this is a stupid question. I'm a novice at physics. I have read the article about entanglement and EPR paradox. The spin of two particles is measured when they are very far apart, and ...
0
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3answers
337 views

Why does a violation of locality not imply a violation of relativity?

This question is closely related to: What counts as information? Taking the specific example, again, of the EPR experiment. I think everyone agrees on the following: The act of measuring the ...
0
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1answer
42 views

Angular momentum conservation laws and GHZ article (Greenberger et al 1990)

Can anyone recommend a good book or an online source on angular momentum conservation laws in decay processes? I'm writing a master's thesis concerning Bell inequalities and currently working on GHZ ...
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6answers
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What counts as information?

What counts as information? In e.g. the EPR experiment why is one entangled particle knowing instantaneously the state of the other not counted as 'information'. Edit Following a discussion in the ...
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0answers
81 views

Does EPR permit information to travel faster than light? [duplicate]

This question always throws me: Discuss if the EPR paradox violates special relativity? The information of the state of one particle is instantaneously transmitted to the other particle, but does ...
0
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1answer
391 views

How does this youtube video demonstrate quantum entanglement? [closed]

The following is an experiment that shows "spooky action at a distance" of quantum entanglement; that is, when we measure some properties of two entangled photons, we find that measuring property of ...
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0answers
114 views

The “spooky action at a distance” and reference frame

It is often said that the measurement in EPR experiment is instant, as somehow described as "spooky action at a distance". However, the notation of equal time depends on reference frame, according to ...
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6answers
760 views

Explanation for the EPR-like paradox

I am trying to understand the process of Quantum Entanglement for use in Quantum computers. The problem I have is this: Suppose some nuclear process emits an electron-positron pair. Now after ...
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1answer
817 views

Some applications of the Einstein-Podolsky-Rosen (EPR) paradox?

If you were to explain the Einstein-Podolsky-Rosen paradox to high school students (age 16, with no particular strength in math), what kind of intuitive example would you provide to make things ...
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3answers
855 views

EPR Paradox resolution: the spin is fixed at creation but its measurement isn't?

The Wikipedia article on the EPR paradox uses the example of an electron and positron created from a common source, each moving in an opposite direction to the other. Detector A is used to measure the ...
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5answers
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What was the need for doing experiments to prove quantum entanglement?

This question comes from someone who is interested in Physics but with no theoretical background. In 1936, EPR presented the thought experiment which later came to be known and quantum entanglement. ...