Quantum Entanglement: Explained & Debunked - Quantum Entanglement & Bell Test Experiments

Aimed at the intelligent lay person & unlike most other quantum entanglement videos, this does not miss out vital information in favour of over simplification. We explain the 'spooky action at a distance' quantum effect (in Bell test experiments) that underpins quantum computing. We also explore Einstein's claim that such results can be explained using local hidden variables.

ALSO SEE MY LATEST VIDEOS ABOUT BELL TESTS:

[KarmaPeny]

Thank you for watching my Entanglement video. ALSO SEE MY LATEST VIDEOS ABOUT BELL TESTS:



It is claimed that Bell test experiments provide conclusive proof that there must be some mysterious connection between entangled particles, even when those particles are in different physical locations. But if the probability of a particle being detected is affected by a property determined at creation (such as the particles having a small detectable area or a large detectable area) then this could be used to explain Bell test experiment results without any mysterious connection between the particles.

By using this ‘detection probability’ we can create a local hidden variable solution that is BETTER than Quantum Mechanics (QM) at predicting the results of Bell test experiments. Not only does it predict the observed correlations for ALL of the usual Bell test angles, but it also predicts a significant amount of 1-sided detections (where a photon is detected in one arm of the experiment but its entangled partner is not detected at all in the other arm of the experiment). In comparison, QM can predict the correlations but it fails to predict the 1-sided detections.

This appears to favour Albert Einstein’s (& Rosen’s & Podolsky’s) hidden variables argument over Niels Bohr’s Quantum Mechanics argument. But this ‘detection probability’ was not given due consideration when Bell test experiments were first performed. Instead, they assumed that the cases of ‘detected at both sides’ were a ‘fair sample’ of what the complete set of result would have been if they had managed to detected all of the photons.

In other words, they decided to ignore a huge amount of the real results, writing them off as just random experimental errors that didn't really count. This allowed them to argue that the particles were spookily acting together as a single entity. Bell's inequality tells us that it is mathematically impossible to devise a local hidden variable solution without any 1-sided detections, and so the easy way to claim a news-worthy victory for QM was to completely disregard the 1-sided detections. This made sensational news, and it was widely publicised that Bohr was right and Einstein was wrong.

Sadly, nowadays when the average lay person searches for information about quantum entanglement they get bombarded by articles and videos that tout the popular misconception that experimental results prove that Einstein was wrong and that the existence of weird spooky quantum entanglement is an indisputable fact. This is reinforced by videos that give the highly misleading impression that detection at both sides always works.

The detection issue was sidelined by grouping it with a load of ridiculous sounding ‘loopholes’. Most loopholes sound just as weird as the QM explanation itself. Several complicated experimental set-ups have been performed in order to close these crazy sounding loopholes. These often sound sensational and so attract a lot of publicity. But what we don't see is any straight forward evidence that would rule out the most obvious classical physics explanation… which is that entangled particles might have a property that relates to their probability of being detected, and that the particles simply acquire their properties upon creation. Contrary to popular belief and the sensational headlines, such evidence has never been produced to my knowledge.

The “freedom-of-choice loophole” is what is claimed to be closed by using quasar light that has travelled billions of light years to control what properties are measured. But I don’t think that anyone seriously believes that there might be some really strong connection between the sub-atomic process that generates the entangled particles and the human-devised selection process that determines what angles will be chosen & when they change during the experiment. Another highly publicised experiment addressing this loophole was called 'the BIG Bell Test' in which 'human randomness' was used to control which angles were used as the settings at each arm of the experiment.

Then we have the “communication loophole” which is that the entangled particles are somehow communicating with each other at a distance, which would be limited by the speed of light. These exotic so-called 'loopholes' get a lot of attention and often lead to sensational news headlines, but they are worse than a complete waste of time because they divert attention away from the most obvious of explanations (which is that the particles simply acquire their properties upon creation).

There have been some experiments in recent years that have claimed to close the detection loophole but they really don't. So I would also advise you to be very sceptical of claims that some complicated experiment is 'loophole free' or that it has closed the detection loophole.

For example, a supposedly 'loophole free' experiment performed in 2015 involved measuring entangling spins in diamonds separated by 1.28km. They had a very high efficiency for reading the spin which they claimed closed the detection loophole. But they only attempt to measure these spins when photons from each diamond had both been detected at a third location, whereby there is the possibility of causing some correlation to the previous settings used.

Another claim was that an experiment using trapped ions practically detected ALL entangled pairs. Even though the experiment involved ions, the method of detection involved counting photons. A very low count of photons was taken as two down (or 'dark') states detected, a medium count was taken as a down at one side and an up (or 'bright') state at the other, and a high count of photons was taken to be an up state at both sides. The results were examined to see what correspondence was found. But a key feature of a Bell test should be completely independent measurements for each entangled particle. Here we didn't have independent measurements; we had a single measurement that we have to interpret as two measurements. The act of taking such a combined measurement could be the reason we see a correlation.


EDIT 02 Dec 2019
Some people have mentioned the 2015 loophole-free experiment by Bas Hensen (at Delft). Maybe I cannot explain it, but I can construct an argument that might make their result sound less impressive...

Say we construct a Bell test that, by natural variance, will violate the CHSH inequality about 50% of the time. So with the box-like arrangement they used at Delft, at side A an input of 0 could give an output of +1, but an input of 1 could produce an output of -1 or +1 chosen at random. At side B an input of 0 could give an output of +1 and an input of 1 could give an output of +1.

Then on average S would equal 2, but due to variance caused by random choices we could achieve S values of greater than or less than 2. Then with 245 trials where 61 of these trials contribute to the negative term in the inequality, then by my calculations we could get an S value that exceeds 2.422 once in every 86 attempts.

And so in order to achieve their result we might have to perform a lot of attempts, but eventually we would be bound to succeed. Hensen's team were ready to start in September 2014, but they were tuning the equipment for about 6 months before they finally got this S = 2.422 figure in June 2015. Since it is expected to be very difficult to violate the inequality, a large number of failures during the 'tuning' would not have seemed unusual. After all this time, effort and expense tuning the system, why did they not collect more results? Bas Hensen explained that the longer the experiment went on, the greater the danger of a silent component failure that would invalidate the whole run. But he did not explain why he could not have performed several runs, one after another. All these things are consistent with a natural variance explanation.

[CristianKlein]

Thanks a lot for this video. I'm nowhere near being able to weight in the evidence for or against non-locality. However, I find it refreshing that someone takes hidden variables as a serious alternative. It almost feels like physicist are running around with banners "Keep quantum mechanics spooky".

[ChrisHanks_ColonelOfTruth]

It's remarkable that a "debunking" video would also contain YouTube's best explanation of the phenomenon being debunked. Have you published this solution anywhere?

[vindictiveDOOM]

Dude IV been saying this shit wasn't right for years. But my professors are like shut up dummy.

[glenfoord]

2 identical boxes, one with an apple inside, one with a banana. I send a random box to Bob on mars.
I open my box and "faster than the speed of light" I know Bob has a banana.
But he really has a dead cat.

[marxug]

Looking for videos on Bell’s Inequality I stumbled on yours, and then down a mini-rabbithole on your critique of infinity... I just have to say, WOW. Your highly abstract mathematics (to me, layperson) seem to have a hard experimental testability, while the ever-elusive quantum computers seem to be chasing their own tails in practice. Perhaps for the reasons you cite? I’m by intuition swayed by Hidden Variables, just because I just don’t see why they can’t produce a nice probabilistic sine wave as well as QM is alleged to. Though I admit I’m well out of my depth mathematically.

[Acein]

I have never accepted 'instantaneous action at a distance' without a proper explanation. I have watched many videos on entanglement and it seems all believe the 'instantaneous action at a distance' story but not one could explain why or how it happens. After a while one puts it into the 'mysteries of the universe - to be determined later' category, like dark energy, string theory, the expanding universe, ect., ect.

[DavidGP]

Wow, finally a channel with real SUBSTANCE on that Non-locality b...s...
Thank you very much. I subscribed and can't wait to come back regularly in order to watch all of your videos.

[KipIngram]

If there is no entanglement the quantum computing algorithms such as Shor's algorithm for factoring won't work - a critical step of the process is the entanglement of the output qubits. But IBM has built a 7-qubit quantum computer using a test tube of a custom chemical and nuclear magnetic resonance techniques for operating. Seven is the number needed to factor the number 15 - they have implemented Shor's algorithm and successfully obtained the factors using it. So clearly the entanglement occurred as expected. Of course, they could have cheated - we can all factor 15. But I highly doubt that happened.

[njwildberger]

Nice explanation. Just a small observation: the angles involved are perhaps not necessary, it seems that only the cos^2(theta) values are relevant. In other words this could perhaps be considered in the context of rational trigonometry, where spreads replace angles.

[zholud]

Bravo. My background is mathematical statistics and I have real trouble understanding how Bell’s experiment disproves hidden variables, and the flaw seems to me to be exactly what you present, yet I haven’t done careful calculations. I wish you make an attempt to turn it into a publication.

[richarddeese]

I applaud your attempt to explain quantum entanglement by conventional processes. It is always the job of scientists to test & to question, even to the point of trying to poke holes in their own ideas before going forward with them. I myself am not qualified to make any judgement in this particular case, however. I can only say that if one tilts at windmills long enough, one is bound to hit something! Thanks for the video & keep on questioning things. It's your right & you duty. Rikki Tikki.

[PasseScience]

It's not new! (sorry, it's a clever Idea I am sure you thought about it on your own, in fact I did as well myself some years ago). *I put all the source links in a reply to this com because else you'll not see it (will go in spam)* . At the end you say it's not the detection loophole, but in fact, it is. Detection loohope is exactly that, this logical argument, based on the fact that you can see non detection not like something missing but like an expressed value "invisible" of the particules. (If you have seen something else it's from someone that did not get the trick). It was first propose if I remember well arround 1970 by Pearle. But you have more recent papers with the same idea by exemple here: LINK.
At the end of the video you say something which is some kind of a lie by omission. Yes something else that 100% detection ensure to be able to violate CHSH, to get classically 2+epsilon. But's a lie because experimentally we do not have 2+epsilon we have 2.42 (0.42 is not epsilon) and here it's a little different, you can have even 90% detection only and still proove that you cannot obtain 2.42 by this kind of trick. And here you can have a recent paper that covers it with a detection rate of 96% and 2.42 and you cannot obtain that with your model (try to have it).
LINK.
But what does it proove? Scientific consensus will be careful on that by saying only that it disprove some range of explaination, not claiming that it prooves a specitif dynamic.
Personnally the hypothesis I prefer to question in the Bell claim is the ability to have independant perfect source of randomness (or free will) at both end of the experiment. In a perfectly deterministic world, if this assumption cannot be sustained, then it's easy to break a Bell inequality. If you see what I mean (pair creation could partially guess what will be done to them because if the get some data from the environement, what will happen can be deterministically deduced). There is a lot to think in this direction a lot of logical stuff to study, by example what is the exact amount of correlation we need to have between the pair creation and the reading choice at both ends to get the same violation etc... So personnally I would not describe entanglement like a spooky action at distance, I would describe that as *what we would obtain if the particle had at creation time a way to partially deduce what will happen next* . (which is not magic in a deterministic world and what would explain why we cannot use it to transfer data)

[gyou]

So obvious there's no spooky action at a distance. Particularly when it suggests changing the past. Your answer seems way more likely.

[BR-hiyt]

Of course he is CORRECT (pls excuse my last comments in another video).

The polarisations of the photons is known but "behind the scenes" in the same way that pixel colours are known even though they might not be showing on a screen at a given time.
(ask me why, no space to explain it here, but its very EASY, I can tell you)

[aclearlight]

Nicely done! So often the practical realities of non-ideal measurement efficiencies go completely unmentioned in overly-simple presentations on QM and non-scientists come away with a false of how "worked out" it all is. You've done a real service here.

[ernestcote]

Exactly! I was just making sure my theory on quantum entanglement was in parallel with this video- and it is

[realcygnus]

Interesting ! any of you thumbs downers or anyone who understands QM @ like a grad/grad+ level explain precisely where/how he went wrong ? It sounds plausible to me, perhaps he is onto something. Of course I'm quite skeptical based on how huge of a deal it would be alone. btw, I see this post is over a year old now, have you made any progress KP ?

[Roedygr]

What do scientists researching this think? I hope you are right. Instantaneous action at a distance seems so unlikely.

[bustercam]

This looks interesting, but it does not really explain any physics. That's the problem with all of these ideas including the original Bell inequality.