Bell Definition and 230 Threads

Has anyone else tried to make sense of the Clauser, Horne, Shimony, Holt derivation of Bell's inequality (Physics. Rev. Left. 23, 15, 1969)? The CHSH version is said to be a more practical application of Bell's inequality, which could be used to describe the polarization correlations that Aspect...

I recently revisited Bell's Spaceship Paradox, and I have a few questions about it that I may ask later, but there's one that I can ask now In Bell's Spaceship Paradox, two ships, separated by space, must begin accelerating simultaneously. After learning about simultaneity conventions and the...

I have watched videos on Bell's Theorem and quantum entanglement. What I don't quite get is: if a pair of particles are created and separated and then we measure one we already know the other particle has the opposite orientation. How do we know for sure that the first particle we measure does...

Could someone please clarify a question that I had? Is it true that 3 or more electrons/particles can be described under one wavefunction, making them entangled? If so, could you use Bell's principles of the comparison of their states like their spin, polarization or position to see if two out...

Hello I am MOHD HANZALA I worked on bell's inequality where we measure spin of electron along different basis leading to the bell's inequality . My question is that can we prove bell's inequality through proton or neutron or other particle??

A question that might occur to anyone reading about the Bell Spaceship Paradox is, can we construct a coordinate chart in which all of the Bell observers (i.e., observers following worldlines like those of the spaceships in the "paradox" scenario) are "at rest"? I put "at rest" in scare-quotes...

Was trying to understand the inequality test. The only article ever that I've found that explains it simply is the 1981 article, Bringing home the atomic world: Quantum Mysteries For Anybody. All other explanations require trust and understanding of polarisation, which is a huge deal. So i now...

Can entanglement be detected in a single Bell pair? The canonical answer is NO, you can only see the entanglement in an ensemble of Bell pairs. For example, you could look at a stream of photon pairs coming from a PDC source. If you apply the CHSH formula (usually presented as an "S" value)...

Hi Pfs, consider a pair of maximally entangled photons where the total momentum is null and the same thing for the total angular momentum. I suppose that this pair is like an universe: nothing outside the pair acts on it except maybe a device for the measurement of these two properties (no local...

Electrons in diamonds are not entangled. Is above statement correct? Spin of emitted fotons if detected separately would not show any correlation? Is above statement correct? Is there assumption that spin of emitted fotons cannot change when reflecting or passing through beam spliter? Or...

See for the article https://www.mdpi.com/1099-4300/24/10/1380 This is a review devoted to the complementarity-contextuality interplay with connection to the Bell inequalities. Starting discussion with complementarity, we point out to contextuality as its seed. {\it Bohr-contextuality} is...

vhttps://play.lnu.se/media/t/0_hgz7034c A.Zeilinger: The Future of Bell Experiments. https://play.lnu.se/media/t/0_6jkhpefo G. Weihs: Violation of Bell’s Inequality under Strict Einstein Locality Conditions https://play.lnu.se/media/t/0_q2r30syq R. Hanson: From the first loophole-free Bell...

I just read an article in Quantum Magazine about "unitary" results and how this is tied to looking at the reversibility of quantum events. It provided an easy-to-understand mechanism for tracking the effects of adding information to a fictional universe. The example they gave for detecting a...

Consider experiments that demonstrate violations of Bell inequalities. I'm wondering about the spatial extent of the wave function of the particles BEFORE measurement. I assume the spatial extent is "very large," and my main question is whether they overlap. If the wave functions do overlap...

If Ma Bell had not been broken up would we have smartphones today?

Hi. In the context of Bell-like inequalities, the words to use seem to be "realism", "locality", "contextuality", "definiteness" and of course their negations. I have rarely seen those terms in classical physics (except maybe locality) before the Bell context. In classical physics (and...

For some reason on this forums here I found some weird opinions that Bell's inequality were somehow disqualifying classical probability theory in general rather then showing merely the limits of locality. I do no understand where that misunderstanding comes from, so I decided to find out. Let's...

When I think about it my biggest issue with the interpretation of QT can be boiled down to this question. There are the axioms of measurement in QT, which have their limiting nature and claim to be the only way to extract information from a quantum system - but that is just a claim with enough...

Qutools makes quantum physics kits for educational purposes. Its quED kit is designed to help students learn about entanglement by performing Bell tests. In the manual section 5.1 it describes "the simplest test to verify entanglement of photon pairs." My question is if the entangled photons...

Hello, In this thesis https://tel.archives-ouvertes.fr/tel-01743877/document at "1.2.2 Bell inequalities" page 7-8 it's define a correlation function : C(x y) = P(+ + |x y) + P(− − |x y) − P(+ − |x y) − P(− + |x y), with −1 ≤ C(x y) ≤ 1. How do one get to this relationship −1 ≤ C(x y) ≤ 1 ...

Loosely speaking, the Bell theorem says that any theory making the same measurable predictions as QM must necessarily be "nonlocal" in the Bell sense. (Here Bell locality is different from other notions of locality such as signal locality or locality of the Lagrangian. By the Bell theorem, I...

Hello. A friend and I are having a good-natured argument about tests of Bell's Theorem and he has directed me to this link. http://electron6.phys.utk.edu/phys250/modules/module 3/entangled_electrons.htm Our understanding of quantum physics should be considered as Basic. What we would like to...

This source http://sustainableaviation.org/sas2017/session/prandtl-wing-maximum-efficiency/index.html claims : "Bell lift distribution can be applied to propulsion systems (no more “minimum induced loss”). We believe this results in a gain of 15.4% thrust for the same input torque/power." Bell...

There is something I don't understand called CV Bell state measurement. In these two experiments they get two entangled beams "by overlapping phase-squeezed light with amplitude squeezed light with a phase difference of pi/2 at a 50-50 beamsplitter" See Figure 11...

Hi Pf I am looking at the figure in wiki about quantum teleportation. https://en.wikipedia.org/wiki/File:Quantum_teleportation_diagram.PNG A wants to send a qubit to B . She receives another qubit from a spdc. so she has to make a Bell measurement on them. Has these qbits to be close in space...

I have been thinking about the Violation of bell inequalities , trying to justify how non locality can be determined from violation of bell tests. I have been through Dr. Chinese page which has partially convinced me that there can be no hidden variables , but I need to understand what...

I took statistics in university about two years ago, but I'm rusty. I was trying to write a zero player game - except sometimes, the player can control one of the characters, and I needed to be able to compute these probabilities. That said, I almost put this in homework help, but it is not...

Given the Bell State in Z basis ##\psi = (a\uparrow \downarrow - b\downarrow \uparrow )## where ##a^2+b^2=1##. Now Alice has one particle and sends the other to Bob. Suppose Alice decides to measure her particle in Z direction. Thus entanglement collapses. Query: 1. How do we know which...

I'm thinking of using an upside down bucket placed at a depth of about 1 meter as a diving bell. Then I want to connect a garden hose pipe to a snorkel and put the other end of the hose pipe into the diving bell. I simply want more time and a bit of mobility under water in order to do a job. I...

I would like to pose a question (previously posed to DrChinese in a personal message) regarding Bell Locality. From PeterDonis in another thread: Bell assumes that local realism requires the factorizability of the joint probability function. Most of the efforts to justify this assumption have...

I'm not following the above quote about free will "This fundamental assumption is essential to doing science" If I perform experiments and find that conditions X are followed by conditions Y and Y=F(X) (or the probabilistic analog for QM), haven't I done science, independent of how much my free...

Usually questions I have of this nature are down to my limited understanding of the concepts, and this may be no different. Based on my understanding of the Block Universe interpretation of relativity, it appears to me as though there is a conflict between Bell tests and the Block Universe. To...

Do all stars in their life cycle (t) emit energy (E) that follow a bell shape curve? If yes, is the curve symmetrical always? How is this related to nuclear and thermal time scale?

I am wondering what happens in the case of 100 entangled photons with a polarization angle of 0 degrees (or 0 and 90) that interact with Alice at 22,5 degrees and Bob at 45 degrees in a Bell Experiment. Do I get a count of 85 for Alice and 50 for Bob, which means a maximum coincidence count...

This bother me too much. A black body is said to absorb every incoming radiation. Looking at absorptance we have : A=Φabs/Φreceived So if a Black body absorbs everything we have A=1 Φ is a flux meaning object/time. This means that whatever the wavelength a black body will absorb the maximal...

Summary: how to apply the the changes in frequency one can hear when a church bell is swinging through the air onto other acoustic sounds in a computer? Hello all, new to this forum. For an (art) sound installation I would like to apply the the changes in frequency one can hear when a church...

Hi, Translated from German magazine "Spektrum der Wissenschaft", September 2009, p. 33 (original see below): That doesn't sound right. EPR even have "physical reality" in the title, though they might not mean with it the exact same thing as Bell. Why would we need Bell's argument if EPR...

Continue reading...

Hi everyone! Sorry for the bad english! I'm trying to understand the "delayed choice entanglement swapping" (avaliable in https://arxiv.org/abs/1203.4834 ) and (long story short) , in the article we have pairs of photons that are entangled in the ## \phi \pm ## Bell state and the photons...

A large portion of physicists thinks that Bell's theorem shows that reality does not exist. Another large portion of physicists thinks that reality is not an assumption of Bell's theorem, so that Bell's theorem just proves nonlocality, period. A third large portion of physicists thinks that both...

In most popular explanations of entanglement, the quantum information of an entangled two-particle system changes without regard to the distance between the two particles. The following paper seems (to my unprofessional eye) to be questioning this interpretation...

hello all so i have been messing about with a homemade franklin bell. It is being charged with an electric fly swatter. I have been wondering if the neutral ball a the center should have any preference as to which side it would be attracted to FIRST. In my head i think it should not matter...

I am new to these forums - if I have posted in the wrong place please let me know. Standard 3D Gaussian bell: z = e^-(x^2) * e^-(y^2) From along the z-axis this looks "round". I would like a generalized f(x, y) which would look egg-shaped from above - possibly quite distorted.. I thought at...

Is the pressure due to the hot gas exhaust stream on the inside walls of a rocket motor bell nozzle positive or negative? Does the rocket exhaust exert a outward pressure on the nozzle walls due to the sheer volume of the exhaust gases or is the pressure a negative one due to the exhaust stream...

Not sure if this reference has been posted yet, but I just saw it come through and thought I'd share. This is the "Big Bell Test Collaboration" using measurement choices provided by persons (as opposed to computer generated "random" choices). (The authors are a virtual who's who in the world...

EDIT: I realize now that I have fundamentally misunderstood a crucial aspect of deriving the Bell inequality for this case which is the existence of the third axis. The setup of the problem did state that the axes were chosen at random. Therefore I can't just look at the possibility of choosing...

This question came up in another thread. I will post again the link to Nick Herbert's proof here: https://www.physicsforums.com/threads/a-simple-proof-of-bells-theorem.417173/#post-2817138 I don't see where the probability shows up in Nick Herbert's proof. For discussion of Eberhard's proof I...

I need help in explaining how electric bell uses motor effect.

I am no expert on the nuances of assumptions of various formulations of Bell theorem(s), but wonder if the following model is adequate to explain the correlations without any non-local features. If this is a known, flawed, approach, a pointer to its refutation (or an explanation) would be...

Bell's Inequality, P(a,b)-P(a,d)+P(c,b)+P(c,d) is calculated as: S = a*b - a*d + c*b + c*d <= 2. It is valid for all values of a, b, c and d between -1 and +1 It is also valid for counts, a=a's counts/total counts of a,b,c &d. b, c,and d are derived similarly. Negative counts are not allowed...