Superposition of Quantum States
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- čas přidán 8. 08. 2018
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Quantum Superposition and the Stern-Gerlach Experiment.
Allan Adam's MIT lecture:
• Lecture 1: Introductio...
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This is the beginning of a quantum physics series I'm starting on the channel. In future videos we will explore the physics and mathematics behind the results of this experiment, plus much more. Please let me know if you have any requests for the quantum series!
I would like to see a comparison between the Copenhagen interpretation and pilot wave theory.
I never really understood why the Copenhagen one was chosen as the accepted interpretation.
Great video btw.
Joe Mccane IMO: after reading Bohm's original papers, I believe that's because the introduction of 'hidden variables' in this interpretation is merely a visual aid of sorts - it's just more stuff to keep track of, and you don't really gain anything except 'intuition'
A jolly good news. If you could keep consistently underlining what is the metaphor you're using related with in the real world (like here spin/color) that'd be real swell, for the people who kinda understand the more advanced version but still want to solidify that understanding with the more metaphoric descriptions you give (and give well). I often find it hard, switching from more advanced vulgarizers to those appealing more to beginners, to see the link between the two versions.
Hello Jade, great video!
It's not directly about quantum maybe but I'd appreciate a video about Cherenkov radiation.
Looking forward for new videos. Take care!
Great video, i love physics and chemestry and i would like to learn more about molecular orbitals theorty, which books doy you recommend me?
I once found a nice way to wrap my mind around the "can't know both" thing:
Imagine you see a very fast car, you want to take a picture of it, to know both where it is and how fast it is going.
If the car comes out blurry, you have some idea of the average speed of the car (width of the blur divided by the lens aperture time), but have some uncertainty on where exactly the car was during the shot.
If the car comes out sharp, then you know exactly where it was, but with no blur, you can't know how fast it was going.
You can't know both because both quantities depend on one another. This helped me *a lot*
Holy sht that just clicked for!!! Thank you!!!
Fulvio Carrus nice analogy, but i have to object on the very last part of your narrative. What i extrapolated out of the two alternatives was that the two quantities *_hide_* one another, so trying to somehow fit two (independent IMO!) properties in just one "snapshot" will not work.
Well damn thanks so very much dude for this clear explaination
if you have 3 cameras,the frist see the shape,the second see the speed, and the third see another shape you cant explain that
omg i finally understand it now thanks to ur comment thanks so much for sharing!!
General Physics I: Classical Mechanics
General Physics II: Electromagnetism
Modern Physics III: Forget what you have learnt and start from square one
lol pretty much
or from the circle one?
Yep exactly and that’s why I’m here.
I feel like I'm being pranked by the universe.
Wait till you see quantum electrodynamics
How so?
I think you meant by God!
I'm back revisiting this a year (and a couple months) later and it's still my favorite video of yours. Well done 😊
It's been a year, come back and enjoy the quality
2:45 _"The actual mechanisms of the machine don't matter at all."_ This is a point that's really hard for newcomers to accept, but needs to be made. Thank you for saying it.
The Science Asylum your videos are great asylum and pls talk a bit more about astrology
How do we know this though? I know "hidden variable" theories aren't very popular among quantum physicists but I don't understand why. I've heard that someone (I don't remember the name) proved that local (as opposed to global) hidden variables couldn't be the explanation but how did he do this? How can we possibly know for sure (let alone prove) that we aren't somehow affecting particles every time we measure them, even if it seems like we aren't? I'm genuinely really curious about this and I've never gotten a decent explanation.
Mikayla Eckel Cifrese : This is a good explanation of the disproving of hidden variables:
czcams.com/video/ZuvK-od647c/video.html
it's just lasers and mirrors, but it doesn't matter at all.
It doesn't? It's just because if you check a green particle's shape you tamper with it and causes it to become randomly green or blue, no?
I just subscribed about a week a ago and have already watched many videos some more than once. So glad I found this channel. Why didn't I find this channel sooner but better late than never.
Even more confusing is a 8:30, the Neutrons became Electrons. Then at 8:46 they became Neutrons again.
Heyu Deuphus She probably meant to say that that's how it happens in the real world XD
Well there was only a 50% chance she was going to say neutrons again anyway.
Yeah I was going to say the same too
Although I have heard this type of explanation before, this is the best presentation of it I have seen. Thank you for posting it.
I saw the MIT lecture like 3 times, to understand your animations just made my concepts more concrete
Quantum physics series!!! I'm so excited! This has become my favorite channel on CZcams and I'm ecstatic every time I see an update. Keep up the awesome!
aww really?! that means so much n_n
This is a really interesting new format. I feel like you could use it on occasion, in addition to your regular videos, especially to make this kind of stuff more accessible to those less knowledgable in this field (e.g. myself)
I love this video!! I think you did a great job of explaining superposition!
Another great video, thanks! These quantum ideas have never seemed that strange to me... in my tradition, we often treat the whole world that way. It makes a lot of survival tasks easier. The harder part is keeping track of what you already know :)
I just love your videos! Please keep them coming ❤️
This was an interesting way to explain it! Never heard this version, great job! Looking forward to the rest of the series!
Quantum physics was originated from Hinduism.
Proof : See the quotes of neils bohr, schrodinger, Oppenheimer, Einstein, Nicola tesla, etc..
I've never taken a physics course (I'm a musician) but for some reason I'm curious about math and science. I like to watch your channel, PBS space-time and Fermi Labs. This is the one that explained superposition in a way I can wrap my head around. Well done, thanks!
This video follows Prof Allan's quantum mechanics course (MIT OCW) very closely. It is really beneficial for me to see this video after the lecture. It cleared all my doubts.
This is such a good video! Thanks for explaining it this well :)
Great video Jade! I think the poll that took place at the side really kept me attentive throughout the video.
You make quantum physics so understandable and I’m so interested ! Thank you!
That was great! Terrific Job! Thank You again. Keep them coming.I,😄love it.
Once again, your explanations are just perfect...
Congrats for the video and the channel! I came up with it right after watching Allan Adams's introduction to QM lecture. While watching his, I thought it would be nicer to replace his hardness/softness property with a shape property. So I think you nailed it changing that part, making it even easier to see the point.
I wonder if you have any video or know of a video that explains how the real boxes work. And what the real neutrons or electrons properties are?? Thank you for sharing such interesting knowledge in such an easy to understand way! keep it up!
This was really very enlightening. Thank you!
Nice video Jade.. 👍
N tons of thanks for introducing Alan.
Excellent explanation. Now that I (and I guess most of the viewers) understand the concept of superposition, It would be nice to see a video with you explaining the real experiment. I also fully understand when you said that we need to re-wire our brain to make quantum mechanics intuitive. I speak Portuguese as my original language, when I learnt English I had to do that re-wiring, because verbs and nouns are in different positions in the phrase in comparison to Portuguese. Nice video! :)
at 4:31 do you only send the circle shaped neutrons into the second color box or do you send both shapes?
Wow i'm back after some months and i see your channel exploded! Congrats on 33k subs :D. So awesome to see that here and there it actualy happens, but with your content is was just a quastion of when. Now i almost forgot the funny thing i wanted to write as i saw your title and wanted to ansver the question in it: You are Super on a Quantum level and i stand to my position ;)
Great video and smartly produced. Well done!
hello, in one of your videos you explain part of orbtial's theory, which books do you suggest to study more about molecular orbital's theory
Just came across yout channel, loved your explaining method!
Great content! Keep up the good work! SUBBED!
Thanks for the explanation .... Really appreciate the techniques and methodology to teach
Love it how it is explained, thanks jade..I am not into computer science but I work in the technology infrastructure line.
Fantastic; informative. Thank you for a great presentation.
This video is the best way to explain Quantum Superposition, thanks a lot
Great explanation!
You are doing a really great job here! Awesome channel! 😊 👏
If I could, I would love to subscribe to this channel 10 million times.
Loved all the explanations in this channel so much that I have recommended this channel to everyone whom I know.
Come for the physics, stay for the jade. You're really good at this.
I'm so thrilled to be learning from you. You are so smart and nice.
An excellent teacher. Thank you.
I feel like at the end of these example experiments, you need a machine that tells you either the color or the shape of the neutron. The machines used in the examples are sorters, but sometimes you used them as indicators and sometimes you didn't. For example, in the experiment with the beam splitter, you use the final color sorter to show the outcome of the sorting, but the shape sorter is just used as a sorter, and its outcomes are unknown. It seems like there are assumed machines at the end of these experiments that explicitly give you a shape or a color, but these are not stated. In other words, the sorters are sometimes also being used as indicators and sometimes they are not in these examples. Just something to think about. Great video!
Crap. execute uncertainityprincle.exe failed. Error log location and information simultaneously inaccessible.
I think the most intuitive analogy is with Fourier series (sums of waves). If you sum many "wave properties shape" you could get a peak of the property "colour" and viceversa. So for this two related properties, you can't get a peak in both at the same time. You need many colour waves to get a define shape, and many shape waves to get a colour define. (look for Fourier series on wikipedia can't draw here) Good video!
when a particle is in superposition is it interacting with something?
Thank you for your great explanation! I´m a little less superconfused. But still a bit in terms of what is the consequence of superposition on the events that happen in the real world that is bigger than atoms? :-)
Or is there another video for that question or is there no answer to that question yet?
9:50 will the detectors change the results? since we knew the shape now.
Loved this explanation thanks
Did they take into account the quantum foam? Do you have a link to the construct of the colour and shape box so we can confirm your assumption?
What a great video!! Thank you!
This is one of the best descriptions for the lay person of quantum superposition I have heard. If professors started their discussions about QS this way, I think a lot of people would understand it quicker and with greater easy.
We are hunters by nature. A hunter, regardless of quarry, starts by looking at a general area and then focuses on areas of increasing detail until they find what they are looking for, whether an animal, berry, or a quantum entangled pair. Your approach to the topic follows that path.
equesdeventusoccasus Or they could add Linear Algebra in the curriculum - a class I took _before_ QM 101. Trust me: it _really_ helps
Iago Silva 3 Blue 1 Brown has a similar concept to what Jade is doing with this video. She is merely taking one step further than him.
I think that your idea is great, however, someone with no math or science background can begin to understand what quantum physics is about from a high level here. They can learn the math after they understand the basic concepts.
Not quite - Minute Physics, Susskind's Stanford lectures and elsewhere they talk about the same concepts using the more mundane analogy of polarizers; I don't see what Jade is doing here that's so 'special'
Also, of course I had in mind the people who want to delve deeper into QM - what is not so obvious (to most physicists, anyway) is that QM should be understandable w/o recourse to its math. E.g., "wavefunction collapse" sounds mysterious and exotic, but you can explain all about it using coins or dice
Iago Silva you speak from a point of view that indicates that you have some level of college related to physics (I will also assume you are being figurative in the QM101 statement, as quantum physics and related courses are typically 400+ level courses.)
You, Jade and I all agree that the basic concepts of quantum superposition requires no math. If you do have a college education on the subject, you are fortunate. The overwhelming majority of people require a basic first step into the subject. One that is colorful and interesting, so that they will want to learn more.
That is what makes Jade's video, special. It presents the subject in a way that makes people think, "Hey, this stuff is fascinating and maybe I want to learn more."
9:53 not understanding this part since with the detector set up, it implies that the electron does take one of two paths. Does that mean half electrons are going through both paths?
so what the hell...right!!!!
Ok. I had a look at the lecture you mentioned. I notice there are a few errors. 1: Electron exhibit up and down spin, just two quantities. The idea of colour and shape is derived from the orientation of the magnetic field in the box, not the electron itself. 2: you need to understand spin to get superposition. 3: Neutrons have 1/3 and 2/3 spin, not binary. 4: colour and shape 'machines' are the same thing, orientated at 90 degrees to each other. 5: the machine organises the neutrons by aligning them into Up and Down, it rotates them and so does change their orientation. 6: the mechanism does matter, there is no tiny demon inside the machine, you need to have a magnetic field in a certain orientation for the effect to work. It is completely to do with the orientation of the magnetic field. 7: The reason it is always 50%/50% is due to the wave nature of the electron. Waves go up and down in equal proportion. Therefore, it in not completely random. 8: after the 1st pause, the solution as to why 50% are 'green' and 50% are blue is because the machine reorientates the electron wave, the X, Z, X axis will obviously produce a 50% mix. 9: the machines reorientate the neutrons on the x and z axis, which is why you get the 50%/50% mix. 10: no one has ever isolated a neutron or even a photon. 11: Experiment 2 produces all 'green' neutrons, as the recombination reflects the 'round' neutrons, but not the 'square' ones. The mirror 'inverts' the wave, in the same way that Circular polarization is inverted. As only the 'circular' waves are inverted at the last step, so the result produces all 'green' neutrons. 12: When the 'round' neutrons are blocked, there is no recombination in the final mirror, so all the 'square' neutrons are now polarised in the x-axis, so when passed through the z-axis (colour box') at the end, the result is 50%/50% split. 13: The reason you can't know colour and shape at the same time is because the electron only has 1/2 spin, (neutrons only 2/3 and 1/3). As there is only one property, not 2 as you have suggested. The only difference between 'shape' and 'colour' is the orientation of the magnetic components inside the box at 90 degrees. 14: the path is not a million miles long. 16: you forgot option number 6. You can change the polarisation of the electron/neutron with a mirror, which makes logical sense of reality, once you reintroduce the proven wavelike nature of matter, and stop proposing the neutron is just a particle, like a football, which it is not. Btw, you can't place a detector on both paths, as detection is a destructive process, which is the foundation of the uncertainty principle. 17: No the neutron is not square/circular and blue/green at the same time, which are orientations of spin at 0 degrees and 90 degrees to each other. The up and down spin exist at any orientation until passed through the magnetic field. 18: I am glad you mentioned the Stern-Gerlach experiment.
I think you got this idea from this lecture ocw.mit.edu/courses/8-04-quantum-physics-i-spring-2013/43a8712da99ace660cf042c1f1371b46_MIT8_04S13_Lec01.pdf. The concept of shape and colour does not exist in the physics of the electron. It was fabricated by this guy, apparently just because he believed his students were not intelligent enough to understand the idea of quantum spin.
For a clearer explanation, check out these videos:
czcams.com/video/ZUipVyVOm-Y/video.html
czcams.com/video/PH1FbkLVJU4/video.html
btw: this is not a dig at your understanding of atomic physics, but I have noticed that this concept seems to have created a lot of confusion about the nature of electron spin. Thanks to Allan Adams, who has taken it upon himself to redesign quantum mechanical principles.
In the example when you tested correlation between shape and color the color or shape was preserved after the second pass into the machine. In the second example the color green was not preserved after passing it into the shape machine(the second pass). Why? Is the first example an oversimplification?
I see a similarity in that in both cases the final result preserves the input; a result with both color and shape. Are we assuming that we only learn of the final result and the intermediary results are hidden?
If we cant know the shape and color at the same time then what about the last stage of those two examples?
Update: I think I got it. I got cued into an understanding when you said that having both shapes in the result means we dont know what shape the particle is. Maybe this would have been easier to understand if you emphasized one particle at a time in the whole lecture.
Please could you make a video on quantum computer and why is it way better than regular computer. I like how easy you make the topics.
I'll add it to the list :)
Thank you. I really appreciate it.
You do great stuff on this channel!
you make nice videos, keep making more videos. thanks for explaining such topics.
Hi, I've been wondering about whether A.I. used in humanoid robotics will end up being able to count the way we do? This is related to a VSauce video from 4 years ago called: -
"1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35..."
In that video it is explained how we can immediately count 3 to 5 objects without even thinking about it. Yet, toddlers go through a phase where they count differently to us and young toddlers. Also mentioned is logarithmic perception.
I don't know how to articulate this (wish I had written it down when I orignally thought of it) - but I am sure I am not the first to think about it. Though I am pretty sure it involves more recent understanding (if I have this right?). I should probably read Daniel Dennett?
Goes back to thinking about free will and old determinism/indeterminism questions. And throwing in newer concepts such as entropy of information, chaos theory and unpredictability, that overturn old ways of looking at the question of free will. I.e. I believe thinking about things in a deterministic/indeterministic way is an emergent way of looking at things that obscures the real processes going on underneath (a bit like looking at things in a newtonian way is an emergent reality of the quantum mechanics behind it).
I am essentially wondering if the reason why we can count 3 to 5 objects straight away. But have to think about a number of objects more than that (and loose accuracy at the same time). Is not because of our limitations (though it would be connected). Or because that's the way we have evolved that best suits our survival (though again connected to that). But because of the limitations of information itself?
I am wondering if any number greater than 3 to 5 is really what we think it is? - Could it be that somehow entropy is involved (I am scratching my head and being a bit vague - sorry)? Something anyway, that would mean even an A.I. would have to adopt our senses if you like - regardless of evolution? Or even physical reality? Purely a constraint caused by (the entropy?) of using information?
Sorry. Thanks :P
This was fabulous!
I watced this video twice back to back, then had my dinner and then, read Stern-Gerlach experiment, Heisenberg's uncertainty principle and again watched this video, thus I found that it's like Heisenberg's uncertainty principle which says it is impossible to devise an experiment that can measure simultaneously two complementary variables to arbitrary accuracy. I really appreciate your efforts mam (since I didn't know your name), but this time it really became so tough to understand for me. Again great work as you always do. Good luck.
Yes it is very closely linked with the uncertainty principle. And my name is Jade :)
Hey Jade I watched your video "Quantum bomb tester" that explains quantum superposition very easily.
Another great video! Love the voice.
Yup I am all over the science channels lol
I am really pleased for you clarifying that it's not that we can't know both, it's that the information, in the most literal sense, does not exist.
I think it still makes sense to say it took both paths. The reason is that if you put a detector in, then sure, you will find that it took only one path - but if you detect which one it took, it will come out 50/50 blue/green again.
Your videos are very cool. I'm excited to the next one.
Quantum physics was originated from Hinduism.
Proof : See the quotes of neils bohr, schrodinger, Oppenheimer, Einstein, Nicola tesla, etc..
😭😭😭 so gooood! Finally, I understand what does it mean by superposition.
Good morning to Up and Atom and Brilliant, thank you so much for your Quantum Superposition teaching.
Fantastic 😊 Thankyou, really great work!
Similar to observing particles in the double slit experiment. 👌🏼✨
Yes very similar I just feel like the double slit has been talked about so much! But it is a fascinating experiment.
So this means that by checking the shape you need to interact with it possibly changing its color (or shape) by touching hit? Is that what happens then?
In both experiment 1 and 2, when neutrons come out of the final colour sorting machine, it is shown to be having a certain fixed shape in the animation, shouldn't it be shown as a blurry cloud too since we can't know both the shape and colour at the same time?
For the quiz @ 7:01, I first thought that in the #1 exp, we only had circles and we got 50-50 split.
In the #2 exp, we had both squares and circles and got 100 for green.
So, probably the shapes are doing something.
Therefore, if again we are going to have only one shape then it will give 50-50.
Very interesting video. You also looked very good in this video. The only critic i have is that the lines in the mirror shape in one of the figures logicly should have been turned 90°, since it should let particles from the left pass and not from the bottom. Thus would make the figure fit better with the explenation.
Again, good video and i hope you make more of them.
I really like how your illustration at 4:38 shows the first green blob going through the shape machine and becoming colorless...BUT wouldn't it have been more accurate to show the final 50% green and 50% blue neutrons as back to blob shapes?
8:53 What is a Venn debtor? Is that some kind of deficit in overlapping rings?
Does this have anything to do with the Uncertainty Principle? Or is it something completely different?
Excellent explanation..
you are just amazing, love your videos!!!
Slow down for a hot minute, so your telling me that i can make a demon sort stuff on subatomic levels?
Question if you send a neutron through the shape sorter and it shows square and then send it through a colour sorter and it shows green if you Then resend that same neutron through the shape sorter again does it still come out square or is it possible that it would come out as a circle?
“Anything is possible” a few seconds later, “no curvy turquoise squares allowed” makes sense
Could you explain the Von Neumann chain?
I learned about these experiments in highschool. I am over 35, and the spooky disturbing and charmed feelings, all at the same time, still don't go away...
5:22 “Then they’re all recombined…” if you’re sending one neutron at a time, what are you “recombining” the sent neutron with?
This video is so informative!! Made my day!!! Support to a great creator!✌✌
This is a good overview of quantum uncertainty but I think to really understand what a superposition is it's important to talk about the double-slit experiment. I've never really associated Stern-Gerlach with superposition. Another interesting topic is the nature of polarization and the insights it gives on quantum identity (specifically that it doesn't exist.)
how do we know neutrons are blue and or green and what is thes 2 shape and coloer boxes what do they represent ?
Here to support an awesome creator.
Finally understood thanks to you Maam 🔥
Waiting this for a long time
Loved it ❣
Great video!
the percentages do they add up to Uncertainty principle?
Nope they add up to 100%. I'll do a video on the heisenberg uncertainty principle soon :)
That first 1 minute of your video where you ask everyone watching to forget what they know and stop trying to fit the knowledge into existing moulds is probably the most genius way to start educating anyone on something new.
So, I don't exactly know much about quantum mechanics; mainly just asking this because i'm curious.
On the third experiment where the square neutron path is a million miles long, could the square neutron change its shape/color? Like, can a particle change its properties over a length of time or amount of distance?
Does the time of superposition loops??
Ok, so after sorting the color and shape, if we take a single neutron, say a blue square one, and run it through the machines again, would the outcome be any one of the four possible combinations with a 25% probability of each?
If two electrons are under superposition does that mean in any point in time they are just one electron?
3:38 is this correct? A green square coming out of the blue exit?
Thanks for a great video, if I inderstand this right we will always get a split if we try to observe a different property than what we just measured but is it a presictable split? So if we measure in your example the color, shape and color again and send through and odd number of particals could I predict which bucket of the colors would have the largest number given the color of the first reading of the first partical?
Ps I am very happy for the answer of this to be No :)
In actual experiments and equations there are concrete numerical predictions of probabilities. The 50/50 split you get when measuring spin in two orthogonal directions. But if you use two spin detectors rotated (relative to each other) not by 90 degrees but by some other known angle, you can compute probabilities of the two outcomes, those won't be 50/50 anymore.
When the split is predicted to be 50/50, you can't predict which bucket will get the odd particle, this is random. Only when you fire lots of particles, accumulate more statistics, the counters tend to predicted probabilities.