Marissa Giustina: Significant loophole-free test of Bell’s theorem with entangled photons

Local realism is the worldview in which physical properties of objects exist independently of measurement and where physical influences cannot travel faster than the speed of light. Bell’s theorem states that this worldview is incompatible with the predictions of quantum mechanics, as is expressed in Bell’s inequalities. Previous experiments convincingly supported the quantum predictions. Yet, every experiment requires assumptions that provide loopholes for a local realist explanation. In this paper, I will discuss the recent results from my laboratory, in which we designed an experiment that closes the most significant of these loopholes simultaneously. Using a well-optimized source of entangled photons, rapid setting generation, and highly efficient superconducting detectors, we observe a violation of a Bell inequality with high statistical significance. The purely statistical probability of our results to occur under local realism is exceedingly unlikely, corresponding to an 11.5 standard deviation effect.
Marissa Giustina University of Vienna, Physics
Information-Theoretic Interpretations of Quantum Mechanics: 2016 Annual Philosophy of Physics Conference
June 11-12, 2016
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[@nathanokun8801]

It is interesting that while Bell proved (so far with our current knowledge) that the two entangled particles are INTERNALLY communicating with one-another in some manner, Einstein is STILL CORRECT in that you cannot get any EXTERNALLY OVERLAID information into this communication (the results, though correlated as matching pairs, are still random as to what they are at any time, so you cannot send any useful data on this link, as far as we know now). This "ghostly" super-luminal connection is what made Einstein "agin it", though it still respected his overall rules. This is what makes this effect so frustrating: It is staring you in the face, but you cannot use it for anything that YOU want to do! Is God laughing?

[@oofbruh2607]

Something about listening to smart people talk about complex things is mind boggling and relaxing at the same time

[@jmmjjmmj8994]

A good refreshing break from flat earth debates.

[@SkyNelson]

This was a great paper and great experiment. Thanks for moving the field forward.

[@KeithMakank3]

"Photons are easy to loose" - some LIGHT humour

[@dreamdiction]

Especially as photons don't exist in the first place.

[@MarcusMorgan]

Excellent presentation. Thanks for your careful work.

[@AkamiChannel]

I’m just an interested amateur but this was great, thank you. Wonderful to have stuff like this on KZbin.

[@dixithanoop]

It's mind-blowing to just look at the experiment setup!

[@nicklezetcoccultedtruthpla6312]

Wow! Astonishing work

[@robbie_]

Great presentation. Thanks for sharing.

[@make.and.believe]

Fantastic work. Wonderful presentation. Well constructed experiment.

[@dumankral8812]

thank you so much MARISSA

[@CandidDate]

I'm glad I'm not at the experimental end of things. It takes a lot of willpower and determination to fight the elements (and dust) and get this thing we call reality to yield its secrets. I applaud your research as it is on the cutting edge of the field. I am working on the theoretical end of things, but I hope we will find out someday if Shrodinger's cat is alive or dead. :)

[@jomen112]

Why do you assume the cat exists in the first place?

[@kristopresto339]

Did Shrodinger ever have a cat? I think he made it all up.

[@xoweytre9383]

I Am Shrodingers cat. I don't know if I'm dead or alive.. what do you think?

[@herrietako]

Congratulations Marissa :)

[@DanFrederiksen]

Since the photon wavelength is quite small, is such long photon travel necessary for the experiment or could it equally be determined with just 1cm travel? or even less. Maybe facilitating higher success rate.

[@holdenrobbins852]

I'm still confused why people assume there is some sort of non-local communication occurring. Why is entanglement not like two spinning balls bouncing off each other in different directions? ie. the initial conditions for the "entangled system" is what makes the spin opposite. (not some 'spooky' communcation) I assume this was Einstien's point... there is more likely something more mechanical at work fundamentally, not that the spin isn't set until someone actually observes it.

[@ElefantPenisJr]

They conclude non-local communication because properties like spin not being set till measured is a fundamental axiom of the Copenhagen interpretation of QM. Einstein Podolsky and Rosen built their paradox with this interpretation in mind. I assume you know how you reach a conclusion of non-locality with the Copenhagen interpretation but just in case: Since entanglement allows us to measure one particle and know for certain what the value of its pair will be, we conclude that the act of measurement of a state of particle A makes real (Einstein-Podolsky-Rosen defined a state as real when it has a predictable value) a state of particle B. If A and B are spatially separated such that the information of measurement of A would have had to travel faster than the speed of light in order for B to manifest the property predicted by entanglement, then local realism has been violated. I could be completely wrong since I am just a philosophy student that is way over his head...

[@carly09et]

The spins are +,- but the measure is L R the problem is trying to qualify "+" ...

[@voyagertwoband]

Thank you!

[@indiadad]

There was a gentleman in the audience who asked at the end if entanglement is necessary for such experiments to be meaningful, and Marissa said "no". I don't understand that. I thought entanglement was at the heart of Bell's result.

[@lepidoptera9337]

The way it is usually presented entanglement relies on global symmetries, the generalized Bell's theorem is universal as far as I can tell. It doesn't need an additional symmetry as far as I understand. I might be wrong about that.

[@mediaaccount8390]

The epitome of pure science.

[@Fransamsterdam]

So the result is - as expected I think - a violation of Bell's inequality, which means that we cannot explain quantum theory with hidden variables. Please correct me if I am wrong...

[@Sam_on_YouTube]

Fransamsterdam Close, but not quite. This closed the known possible experimental errors. That means that if you assume there aren't other sources of experimental error, and assume that nature has not conspired to have random number generation systems (and as she pointed out, a similar experiment used a variety of random number generation methods) combine with Bell style experiments to trick us into believing in quantum mechanics, then you cannot have local hidden variables. That is a very strong result, but not quite as strong as what you stated. Bell's theory does no better against solipsism than philosophers do. You can argue it isn't sensible, but you can't prove it outright wrong. It is worth noting that this already covers possible experimental errors that would be pretty far fetched. It is highly improbable that another unknown error would actual cause a perceived violation over and over again when we have 3 experiments eliminating other causes of the violation of the inequality. It's also worth noting that this should be considered together with Kochen-Specker, which adds an additional requirement to hidden variable theories. Not only may they be non-local, but they must also be contextual, meaning that how you conduct the measurement partially determines the result, so the thing being measured doesn't simply have it's own properties. (There's a good chance I'm mistating that, quantum contextuality is at the edge of my understanding of this stuff.)

[@jomen112]

_"Bell's [theorem] does no better against solipsism than philosophers do. You can argue it isn't sensible, but you can't prove it outright wrong."_ Exactly how much more evidence is needed before we can say the predictions made by quantum mechanics are correct - or any other theory at all for that sake?

[@emjay9733]

Cool stuff ⚛️

[@vancamjr]

There’s always seems to be that guy (1:16) who smugly rolls a statement into the form of a question for his own edification. His face, an easy read, speaks volumes.

[@insightfool]

Totally. This guy was so smug he seemed to have no idea how much he is embarrassing himself.

[@wdobni]

so did she prove or disprove bell's theorem? did she prove spooky action at a distance or did she prove nothing goes faster than light?

[@robertbarta2793]

Super interesting. And next time I walk by the Hofburg I will tread more carefully :)

[@robertharlton3850]

I'm also thinking that for entanglement to work, everything, at some level, must be single point.

[@NoActuallyGo-KCUF-Yourself]

And why not fields, strings, or 'branes?

[@Business_Memo]

@@NoActuallyGo-KCUF-Yourself I think Robert's meaning is one mental gymnastic you could do to get around "nonlocality" is assume that "locality" is a flawed concept. But for that to be true, we would have to re-evaluate our concept of spacetime itself, and would totally change our understanding of reality. So Occam's Razor.

[@ivanscottw]

Way over my paygrade ! At this point at 24:31 when she states 'when the apparatus knows what you're doing" is when I got lost ! (since when does a mechanical construct *knows* anything ?)

[@Schmunzel57]

Why can’t the measured entangled photons not be the same photon, bleeding through into the dimension you are measuring in, like a drop of Ink going through thin paper and read able on both sides? I mean, your “making” of entangled photons is like you are on the edge of a paper and the measurements is made from both sides of the paper and the photon only looks like a pair but sinks through the paper instead.

[@Pengochan]

Basically you're describing a form of nonlocality in our space by providing a shortcut between entangled particles (through some higher dimension). Maybe have a look at the Susskind (stanford) lectures on entanglement (and black holes). If i'm understanding him correctly he's basically saying that entanglement (of vacuum states) kind of "knits space together". i.e.: kzbin.info/www/bejne/b5TVmJqlrZqlmMU

[@sementhrower420]

Just to feel like I've contributed to the conversation your question started, it seems like you're thinking about this in a similar fashion as Wheeler did when he concocted the idea of a one-electron-universe. I'm not sure what the conclusion was on the topic, but I recall seeing a PBS Spacetime episode on this. Even if it doesn't help this discussion, it's worth investigating this fascinating mental jiujitsu! :D

[@myREALnameISiAM]

There is ZERO evidence of extra dimensions. All data collected indicates 3D spacial matter evolving through time.

[@deluxeassortment]

Feynman basically laughed off Wheeler's one-electron universe postulate as he suggested it to him, but in the same breath felt Wheeler had suggested something provocative about electron-positron annihilation and admittedly stole the idea for his Nobel Prize speech. That's about all the conjecture it received.

[@metatron5199]

Schmunzel57 as mentioned in the responses already go study EPR=ER

[@EarendilTheMariner]

Is Giustina an engineer or a physicist?

[@bazzmond]

Seems clear that local realism has been violated, but what does this mean, non local realism?

[@z08840]

non realism - locality is protected by special relativity

[@MichaelHarrisIreland]

I think it means that the world we experience isn't exactly real but makes sense to us just because it works on the limited level we need it to. That there are other things going on, below the surface, which makes all our logic built on sand. I don't mean our lives don't work, but just that it is not absolute reality, that there is a more fundamental reality than we know at present. But the fact we've discovered this is sort of amazing, and if it wasn't that way it would be even more frightening... e.g. that we know everything, and everything is as we thought. Instead of being at the end of science and discovery, we seem to be opening another curtain beyond all of our imaginations.

[@metatron5199]

z08840 that one possible interpretation tho there is a lot to say why that seems to say that is silly given all of the other strange features of QM which instead point to abandoning locality instead of realism, must physicists would seem to rather preserve realism due to the fact you enter into having to talk about a lot of seemingly ridiculous concepts by having a non realist theory....

[@proffski]

Sheer genius, thank you!

[@grandunifier3169]

I can't wait for the new generation of particle physicists to replace the old guard... All photons are capable of fusion & fission, it's not that hard to understand...

[@NickyTannock]

I don't know how I'd handle someone like the guy at 1:05:55.

[@TijgerPapa]

I wouldn't know it either, but he does ask an interesting question and I don't think he got a satisfying answer.

[@asherklatchko9567]

the "satisfying answer" is subject to debate. paraphrasing what the guy says is: you create entanglement and (as a result) detect it, what does it have to do with local realism? what the presenter says is: we can only measure the violation of local realism with entanglement and therefore create it.

[@michaelmelgaard1]

Once he made the claim that she was avoiding the question, he revealed himself to be emotionally controlled by a motive. At that moment, he can go find his own "satisfying answer."

[@brandonlewis2599]

I was wondering if that was what was going on... is that kind of thing common?

[@mentalitydesignvideo]

@@michaelmelgaard1 'he revealed himself to be emotionally controlled by a motive' Why would anyone do science if there was no emotionally charged motive? For money? Fame?

[@BarryKort]

In the derivation of Bell's Inequality, he posits a presumptive hidden variable, λ(x,t). In this view, one member of the twin particles has a position +x at time t, while the twin has a position -x at time t. But note that Bell blithely adopts a common master clock, t, so that λ(x,t) can be algebraically canceled out by λ(-x,t), regardless of the function λ(•). If you appreciate that a gravitational gradient perturbs timekeeping so that the particles speeding off in opposite directions age at their own idiosyncratic rates, then one can no longer algebraically cancel out λ. That is, the derivation of Bell's Inequality breaks down; the presumptive hidden variable λ(x,t) remains present. Indeed one can say the hidden variable is time itself. That is, in reality, each particle ages according to its own local clock, rather than being governed by a common master clock. In Aspect's experiment, λ(x,t) could be Maxwell's Equation for the photon, or (equivalently) Feynman's rotating vectors. But recall that photons traversing a gravitational gradient gain or lose energy and thus change their wavelength (or color) accordingly. The two photons are thus represented by sinusoids which are not perfect mirrors of each other and thus cannot be algebraically canceled out. They will have a residual nonzero "beat frequency" which remains present, thus spoiling Bell's convenient cancellation of λ(x,t) midway through his derivation. That's why Bell's Inequality doesn't hold in the real cosmos where there is no universal master clock that keeps identical time everywhere and everywhen. The not-so-hidden variable is time, itself.

[@petros_adamopoulos]

What you mean is that time conspires to make us think local realism is true but also appears to be false whenever we try it. I wonder : what he [time] planning..?

[@brandonlewis2599]

What math (beyond Algebra, Geometry, Trig, and Calculus) does someone need to know to be able to confirm this for themselves?

[@juancarlosrodriguezlasanta7695]

If so particle entanglement is a complete lie!

[@goodchessactor]

Not exactly. It's just counter intuitive. Entangled particles are not just laboratory produced but exist in nature.

[@jjames1977]

A gravitational gradient is not necessary feature of a CHSH type experiment.

[@kirchdubl1652]

so Bell's inequality is valeted or not , what is final outcome ? I though this already has been proved many times and long time ago.

[@lepidoptera9337]

From a physics point of view none of these experiments are worth much. If you do a precision test with photons it still doesn't mean it's tested for electrons. What if I suggest to you that the Higgs field violates Bell's Theorem? How are you going to test that in the lab? Exactly, you aren't going to. At least not with this century's technology. At most you will arrive at probably rather weak indirect limits from deformations of quantum field theory. What if I want you to repeat this experiment with 3eV neutrinos? Good luck with that. This is just one of the reasons why serious physics does not concern itself with these kinds of non-problems. If nature wants to violate the structure of quantum mechanics, then there are far more sensitive tests than Bell's Theorem.

[@Badmanxl5]

I read where Einstein said time is a persistent illusion. But he also connected space-time, is it possible that space is a quantum mechanical illusion of our brains and we really exist in a holographic illusion.

[@schmetterling4477]

Sounds like a good physics joke to me.

[@TheNorgesOption]

Okay, heard enough of the mystical "Spooky Action at a Distance" Quantum Mumbo Jumbo. Here is a No-Go challenge for Bell’s Theorem. The Bell’s Inequalities Challenge - Can one by combining Macroscopic Real Objects with classical wave functions violate Bell’s Inequalities? This can be achieved by using a large pool, small self-propelled model boats that do not have a steering system and a series of short parallel walls that can vibrate and produce waves. First one has to create the parallel walls that are just wide enough so that if a boat is sent on a parallel direction to the canals created that they can reasonably pass through without the boats touching the wall (which would be a fail). Then send the boats on slightly canted angles and using classical wave mechanics most should hit the wall and fail the test and not violate Bell’s Inequalities. Now vibrate those walls in which pressure from the waves creates a low-pressure zone in the center of those walls so that the boats will head that direction in a path that is parallel to the walls. The boats should then be able to Violate Bell’s Inequalities. If that is achievable, then virtually every experiment in quantum physics should be reproducible using just local wave functions.

[@iammatty777169]

According to Professor Rupert Sheldrake, the speed of light is NOT an agreed upon amount. Instead it’s calculated then averaged to whatever it’s supposed to be. Quite surprising. And there’s Maxwells equation, Bearden’s Energy from the Vacuum book And Negentropy. And the other, occulted sciences ? Excellent information and presentation 👍🏽

[@robertharlton3850]

entanglement is limited by the speed of light? Since When?

[@alexanderks7453]

The entangled state information cannot be communicated faster than light. In theory at least.

[@rainertheraven7813]

At the moment of entanglement the states of both particles are fixed. Later measures on one don´t change anything in the other, so there cannot be a instant communication based on entanglement. What you can do is to measure both later and you will find the opposite states which info you could send back on a normal lightspeed channel.

[@simeyD]

Now regarded as out of date LFT Quantum photon theory. Referencing the paper by Jonathan J. Scudgeon & William Siegried "Spit-Fire" McKenzie's Paper [Upon Lambda free-system variant coefficient loss inequalities with regard to distant photon local realism], John. P. Titty Publications, Oxford University (3/23/18).

[@DarwinianUniversal]

Bells Inequality may stem from a force interaction, such as……………….. If you take a pole and stand it balanced on end, then being balanced it expresses no lateral weight. As you lean the pole over incrementally within the earths gravitational field, the poles weight transitions throughout the 90 degree arc, til it is laying down. The interesting aspect is the weight transition is not proportional to the angle. "the incremental weight transition of the pole matches the quantum probability curve". This is an observational FACT, which should spike peoples curiosity!!! Summery A poles incremental weight transition in a gravitational field is an exact match for quantum probability of a photon passing or not passing a polarization filter," at that same respective incremental angle"! Unpacking this consideration "in overly simple terms" The fundamental of the poles weight transition boils down to a consideration of interacting forces. Gravitational force and the poles resistance to that force at various angles, balance and or leverage. The photon hidden variable could use the same model. Just like the pole, the photon is associated with a (position state which requires force to overcome). And the filter (possesses the capacity to impose force that overcomes the photons position state). The hidden variable can stem from this force interaction. An important clue is that the photons do indeed leave the filter having had their position states altered, which is the proposed product should such a force interaction have taken place. So there are an uncanny number of parallels between these two supposedly indifferent systems. The hidden variable as a force interaction. We are after-all talking about (EM force) and its various interactions. (FORCE) being the operative word.

[@drbeanut]

I am finding an issue with the inequality used. You need not only variables for each possible way of measuring the outcome of the photon, but also variables for each orientation of measurement corresponding with an actual outcome. I.e.: N11_1, N12_1, N21_1, N22_1, N11_0, N12_0, N21_0, N22_0. No wonder your inequality is violated, already an abuse of notation and poor assumption!

[@thecowfy]

ok albert said even the most complex theory if it is not able to be explained in simple terms there is nothing to it.ok.i'll listen and see if the logic is simple.

[@KeithMakank3]

Say "though experiment" lol why use the german word?

[@CrapAtPoker]

Alice and Bob i'm so confused jeeez

[@new-knowledge8040]

Tiny 3D human beings are still having a difficult time understanding 4D events.

[@michaeljetnikoff9953]

Hi,photonentangling deluding phenomenon to enable confusion re Grav quantum,but as ST/G,compared with st/g of near local dasplacing +into inner healthiarchicoil,of light ELECMAGGRAV stream,’radiartion,’,as POINPARRICLE spheroidal stretched in photon case in observable in certsin exact equivalent ST/G General field ocean,THART dadcribes quantum function of photon prauduction,in comparison with presumed with photon,from same place,same apparent t,rartRARTIO change t,t=(time)function,thus if same photon split to 2,then bit of each but dasplacing of near inner photon,cf Arrounding effect on other’photon’,said to entangling,but cannot as onley RELARTIVE to dens,dfusn of st/g,ST/G,as thermionic function,of T,or of st/g,local as change in thermionic dficly=t to maesure without change rartRARTIO t,(time) function rel dasplac,refill,repulse of refill prarth of photon,Grav equiv,EQUILIBRINARTION causes complemaentrarum r=relartiv,rartRARTIO,alters maesure,as stabilizing local st/gSTG,EFFECT, rartRARTIO of change in relartiv change in t,’time’function,as sesnsing photon dfrnt to phase reading usual similar to brain filling in gap,reestablum photon of primary production,if use 2 photons from dfrnt light even aperture,straight,or CIRCULARIA altering tunneling of photon in lower st/g rel ST/G field ocean dasplacing affect,effect on each other,as cannot maesure same,t,as is variabl function each photon prarth,rel to resistance,glide of photon,s,prarth,in same change in ‘time’ as relartiv t,dartctr,a=accurum,r=relartiv rarte change in prarth speed in non vacuum,as true vacuum not achievable,as thermionic gradient,graDient,rel Dens,dfusn,lensing in prarth of photon,s,need accurum to 11^7 or not in 7D,accurum thus unreliable results,thanx,bliss, XAMichael

[@Markoul11]

"Did you find or did you cause an entanglement?" LOL! That says it all of how scientific bias can determine the desired outcome of these experiments. 1:05:54