I made a (useless) quantum computer at home 

Part 2 is up: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-tHfGucHtLqo.htmlsi=s-mr2l79q46_QkJ6 If you want to do this experiment at home, you can! It's very simple. All you'll need is: - a weak red laser pointer (the type in cat toys are generally safe) - polarizing film or polarizing filter. If you have polaroid glasses or certain camera ND filters you may already have this. Otherwise it's available on amazon - the half waveplate (the plastic thing) is this one: www.edmundoptics.co.uk/f/polymer-retarder-film/14827/ (λ/2 Retarder Film (WP280)) - You don't need calcite, but if you want to play with it, you can find it on etsy usually. Look for a sample that's exceptionally clear. - BBO: I spent a while messaging people online and had trouble tracking it down :'( I'll settle for KDP or even KTP.

"Mom can we have quantum computer at home?" "We already have quantum computer at home" Quantum computer at home:

I notice that Alice's animation is getting better and better. Hopefully this will continue

"I hate doing experiments." Spoken like a true theorist. Do you know the story of Pauli and Bohr? Whenever Pauli would visit Bohr in Copenhagen, as soon as he crossed the border into Denmark, all of the experiments in Bohr's lab would suddenly break. Somehow I missed your last two videos. Sorry. I'm glad you finally found a happy electron. Usually they are so sad. I also like your new version of Alice. At any rate, I'm glad you're posting again.

That is pure brilliance! I‘m studying form my QC finals at MIT and procrastinated with this video, and this is such an amazing viewpoint! Really excited about part 2!

The next video will be up next week! For everyone who very generously offered to help with the code on my last video- sorry I've taken a while to get back to you! I'll get on it today :)

I love it when i find someone who is so smart that they can explain super complex physics to a normal guy like me. You are inspirational for us nerds who never went to uni.

I really appreciate how you explain complex things so well

i can't describe how much this channel blows my mind. i was screaming at the screen at 19:05 BTW to see our old friends Alice and the negative electron come back animated was really fun, and truly a good strategy too to fortify your "brand" since it is so recognizable for us long time viewers

I just love your videos. they are so fun to watch. please keep doing what you're doing!

I had long ago wondered how plastic polarizers were made. I knew the polymers were alligned, but I didn't know how. It just occured to me that they are aligned by a process similar to making stringed mozzarella chease. Cheese is made up of chains of amino acids that make up the proteins in cheese and start off randomly aligned. Then when you pull a blob of chease in one direction, all the proteins sticking tother and slide past each other are pulled into a common alignment in the direction of the pull. With plastic, a sheet can be made by pressing a blob in one direction. That reduces the polymers degree of freedom to random alignments in two dimentions of a sheet rather than in 3 dimentions of a blobe. Now pulling on a sheet in one direction in the plane of the sheet will mostly align the polymers down to one dimention of freedome. But to achieve better polymer alignment, the long sheet can be cut many times into squares that get stacked with their polymers aligned and gently heated as they are pressed and pulled again to improve the polymers' alignment.

Whatch out for those lasers. Or rather not. I mean, just don't point them at your eyes, they can have quite devastating effects. I'm sure, you're well aware but just thought I'd mention it since some people might want to reproduce your (super cool) experiment! Love your videos, btw!

Glad this got recommended! I took a "NAND to Tetris" style class in undergrad, there's real magic to making a computer. Your generation is lucky enough to be making tabletop quantum computers for cheap!

Super cool! 😀Love your enthusiasm, curiosity and ability to simplify what seems complex. Looking forward to your follow-up. I suspect you are about to cook up more interesting insights 💡

The description of waves operating in 3D and thus made of vectors is the critical piece that's been missing for me since high-school! I finally get it! Thanks so much, such a great explanation!

Q: "Why does light move slower in different mediums?" A: "I have no idea, stop asking me." That gave me a good chuckle xD. But thank you for the answer

The genuine surprise at the end (not being useless after all) is priceless. Thank you! Your excitment is truly entangling 😊

The video is about making a homemade quantum computer. Here are the timestamps for the different sections: 0:00-1:05: Introduction and motivation for making a homemade quantum computer. 1:05-3:20: Explanation of what a qubit is and how it works. 3:20-5:35: Explanation of how light can be used to create qubits. 5:35-8:20: Demonstration of how to filter light to create a specific qubit state. 8:20-11:00: Explanation of how a calcite crystal can be used to perform computations on qubits. 11:00-13:20: Demonstration of how to use a thin calcite crystal to perform a simple computation. 13:20-15:00: Discussion of the limitations of the homemade quantum computer. 15:00-17:00: Conclusion and plans for future videos. I hope this summary is helpful! made by "google bird ai"

I cannot WAIT for the next video! This was honestly the BEST explanation I've seen for me to understand the basics of quantum computing while keeping me engaged throughout and I love how you simplified it to it's core components separately! Really excited to see it in practice! (I do wish that the personification of the wave of light was a bit less terrifying and uncanny though...)

So the light is made of electrons. Got it.

This is the first Looking Glass Universe video and my first real-step into learning about quantum computing. Having graduated HS in 1961 and only completing a few college courses I need things explained very simply and this lady does that in a very entertaining way. I'm looking forward to watching more Looking Glass Universe videos.

Great video. At 94 I am still trying to learn!

I cant wait for someone to get Doom running on a few lasers and sunglasses next year!

20:38 "I definitely would not have come up with it" you just described 99% of my programming career lol. I did not expect this video to go into such depth, but I was not unhappy about it. This subject is honestly borderline impenetrable, I still don't have any idea wtf is happening with light polarization, I understand how it's illustrated but... well... waves are 3D in reality, pictures are 2D, does not compute in brain. And then you have the whole circular polarization thing which is just .. wat?

Wonderful and informative video.

Never Never! show to your audience which may now little about what a laser is, that you check the lasers by looking into them.

Gosh, this is the only person in the world who can possibly explain this extremely simple system to us, are you joking me. Literal professors can’t even come close to this good of an explanation without using words that mean nothing to me. Like, cool they can be both 1 and 0 but like has physically (the particle is vibrating in two directions both horizontal and vertical is all they had to say but noooooo), no professor I’ve seen on RU-vid has ever attempted to explain it as well you have.

It's a bit crazy how divorced physics education is from hands-on experience. It would be nice to play around with the phenomenas we're studying on the blackboard every once in a while.

I worked on a Birefringence Measurement System many years ago. It's awesome to see Birefringence in a real world example!

❤thank you. I been reading so many books they just talk and talk about it, but one shows how it works. I know binary and computer hardware,but how does this work..

I feel like I’m learning about quantum computing in a kindergarten classroom. This is a good thing. I’m understanding everything and loving it

That poor hapless electron. I'm so glad you are making videos again. Your explanations are some of the best on the entire Youbiverse.

When the light passes through the polarizer, why do the electron jiggles “absorb” the wave instead of creating their own wave, like the glass electrons in the “does light slow down” video?

Thank you, young lady. You are shedding "light" on quantum computing :-)

Big fan of the plain English explanation for some of these concepts!

That's what I call a cliff hanger. I guess I need to subscribe now to see the second part 😅

love this concept. btw i'm clipping where you shined the laser on your face to give my lab instructor a heart attack :d

I hate doing (physical) experiments also. I just login to some place, and do it online. (I'm now too lazy.) A few years ago, I used IBMQ. (I think it's called IBM Quantum, now.). All in Python. Introduced me to different gates, such as Hadamard and CNOT gate, the concepts of superposition and entanglement. Can also just do it with linear algebra (matrices), though for only very simple cases. But enough to demonstrate the concepts. This is assuming a STEM background, but without knowledge of quantum computing. (This maybe a little bit more than your intended target audience. But it's another way to get an introduction.)

Hey! This is a great video. Just wondering one thing, how big is the half waveplate that you got? and how long was the shipping?

Thank you for explaining quantum computing so that even kids could understand it. Awesome channel, glad the algorithm found it for me.

I just rewatched your video on your PhD, and from my limited understanding, the computing advantage is that the qubit unlike a digital logic gate has the entire complex plane available which is a massively greater information space; in order to simulate that in it's entirety you need to numerically approximate a hilbert space. The computational difficulty and advantage lies in that rather than using logic gates to do complex matrix calculations, the bits have an intrinsic complex space available. The information is distributed rather than being localized as in digital memory.

Awesome video, thanks! Especially the explanation of the polarization filters was great. Which reminded me of a question I had for a long time that maybe you can help me understand. One famous "popular science" experiment is to take two 90degree polarization filters to block all light. Then insert a 45 degree filter in the middle and some light makes it through. The misleading conclusion is "and isn't it amazing, adding another filter should block even more light, but surprise, surprise, some light makes it through now". I always felt that this conclusion is dishonest. The polarization filter only blocks 100% if offset by 90 degrees. It's like smashing head on against a wall. Adding filters in the middle rotates the light step by step, making sure there's always a non-zero component in the new direction. Then it's totally not surprising that some of the rotated light passes through the last filter, right? It's like adding angled walls so I bounce off at an angle, changing direction each time, before I hit the last wall at an angle instead of smashing it heads on. In my understanding, the "mystery" in this experiment only comes from a deliberately misleading explanation of what the filters do. With the correct explanation, there's nothing surprising going on, is it? Do I see this right or am I missing something?

At some point in this video I accidentally finally understood circularly polarised light while you were moving the fuzzy sticks around. It’s the horizontal and vertical components being out of phase… Thank you so much - 10 years of professors waving their hands and saying “oh and there’s circular polarisation light but don’t think about that” and a RU-vid video makes it click for me

They say that you can tell how much a person understands a topic by how well they can explain it. This is Feynman level of explanation- it is that good! Seems like this is like multiplying two real numbers in spherical space ( at least in part) when compared to multiplying integers in spherical or non Euclidean spherical spaces. Trying to understand where the extra degrees of freedom, sum is a worth more more than the parts comes from, but is not able to be emulated in non quantum space, could definitely use your explanation capabilities to inform the rest of us! Thanks for the great video!

Here's what I find impressive about this presentation: You have made a quantum computer that works at room temperature.

The video title is a total clickbait. The quantum computer you made is not useless as you claim! 😂

I believe it was 3 blue one brown that made a really good series to teach how light is slowing down in a medium.

That was a fun video. Thank you for making it!

If a woman is into crystals..she better be into optical physics too or 👋

Calculations on a home made quantum computer? Woooooow can't wait :)

Banger video! I never really thought about how simple some core concepts of quantum computing can be conceptually, and how immediately accessible it is to demonstrate them!

You are good at explaining difficult things. Thank You.

I love the Win95 UI of the animated computer screen :)

This is wonderful. I just found your channel for the first time. I love the time spent carefully explaining every aspect along the way. You're an awesome educator. Liked and subscribed.

Very cool that you were able to buy some spinors and SU(2) matrices for building a quantum computer. :-)

Great video. What kind of computations were you thinking to do with this setup?

Thanks to your incredible videos and style of explanation, my understanding of quantum mechanics/computing keeps getting better and clearer! My niece too loves your videos and wants to build a quantum computer one day! We both hope you keep these videos coming! :)

You’re my inspiration, I am about to start my undergraduate degree next year and whatever I achieve further down, i owe it to you, since you restored my confidence in the subject despite failing in it multiple times. Thank you and wonderful work!

Loved this video! Can't wait for the next one. I especially love that it allowed us to see some of the "figuring it out" part. Being from the South in the US, I laughed out loud at "the hell?".

Describing qubits in terms of polarized light is the first explanation of quantum computing that begins to make sense to me. Thanks!

You are way too beautiful to be so smart😂😂😂

Amazing video, and the other video about speed of light in water was a great primer. It's awesome to get such a good explanation from someone that actually studied quantum physics without getting bogged down in jargon. Thanks and looking forward to the next episode

Informative and educational, thanks for posting

INCREDIBLE. CONTINUE. You have all my moral support.

i love the cute little Alice animations.

Love the little girl animations.

quantum computing at home.... yay

Hmmm... Price of BBO Calcite must have gone down. I just found one for $300. Well, a few of them with varying time delays, delivery in two weeks.

Your videos are always so well made. Learning made this fun takes a lot work and a lot of skill - and you have both. Thanks!

Fantastic, also I enjoy that you go in to how and why it works, but you also do the real experiment to show it. As a question do the too light beams hit the back stop at the same time after being split?

If you just combine two lasers you won't get superposition, you'll get a "mixed" state of two. So you need to somehow sync the lasers or split the ray of one.

So there's a fundamental issue with the qubit thing. I don't think she understands superposition, which is why quantum computers are different from binary computers. Qubit is badly named becuase it extends "bit" which (in computing terms) is a contraction of "binary digit" binary being one of 2 states, In fact "binary digit" is a bit of an oxymoron as "digit" is actually from the description of the body "digit" as in hand or toe - so one of ten. I digress. Qubit is not one of 2 states (bit) it's a superposition of all states, until it's measured then it collapses into one. You cannot predetermine the result: you can't say I'm mixing a polarisation proportion of vertical with horizonal to give some angle. That's not a qubit, that's just producing light in a deterministic way. People say it's "both zero and one at the same time" because the state is not known, but ultimately when it's measured it's definately one of the states not some proportion. Also why light slows in materials? Has this person not has basic physics at school? REFRACTION!!!

I love ur videos regardless of the outrageous title 😂 , didn't watch it yet just received a notification

AT 21:04, you ask *why does light slow down in a medium?* This is experimental evidence that light is not a particle moving through the medium, or the "empty space" of a vacuum. It shows that both Quantum Mechanics and Einstein SR have major problems, since they are based on particle light and empty space, instead of an EM medium.

What a fascinating explanation and demonstration, thanks!

Wow I can't believe it's been years since I joined this channel! It's been a great ride and I've gone from a guy doing a bachelor's in physics with no clue about his future to a PhD student in quantum gravity with no clue about his future XD. It's been real fun!❤

this channel is wasted opportunity, you can teach more, employ your peers all over the world with good english to teach on various subject. or be like some podcast show showcasing different topics lol instead you upload like once a year lol

By 2025 I should have enough money to start my university courses as well. This is really exciting. Looking forward to the next video.

There seems to be 2 fundamental flaws with that thesis of quantum computing, Firstly the reference table for decoding is not accounted for and secondly the timeframe for lookup to perform decoding is not accounted for. it's an interesting way to create a physical infinity scale but it probably isn't truely infinite and would reach it's limitation based on particle size so it could be used for indexing a large database but then it's really just a different, very inefficient way of computing and not quantum computing.

"I mean, why does light even slow down in a medium in the first place? If you want to know why, well that was a whole other video I did, and the answer basically boils down to, I have no idea, stop asking me." FYI, 3Blue1Brown dropped a useful explainer two weeks ago: "How light can appear faster than c, why it bends, and other questions" Check it out if you haven't already. And if you're just being cheeky and I missed it, well, you're good! 😃

I can't watch your video because I'm a physicist and I know Quantum is woke science.

Fun to imagine. Bonus extra Feynman type guessing a QM 1st of April at Christmas time..? Love the honest presentation of Quantum Computational Logic proving that the design is useless. The Looking Glass Universe analysis is essential to decode the confidence of the Designer, primarily to demonstrate the illusion of separation, as impossible as BBT discrete-ness, and you notice that the Universe is logarithmic condensation modulation in/of instantaneous i-reflection at the Centre of Time Duration Timing, ie purely thermodynamical => mathematical superimposed motion-> Act-uality of relative-timing interference positioning resonance bonding dimensionality. It's not Caterpillar food after all? Allow "Spin" to be the Totality of Singularity-point positioning Conception, of a Looking Glass Universe.., equally useful to imagine. "It's called research" because we don't know what Experiments are for? Serendipity, learning by doing experience and getting a different result is the lottery winner's rationale for gambling. Useless for Quantum Operator Logic. Truth in Labelling? Entanglement entertainment is an experimental success?

Very nicely explained. Some questions: 1. Laser light passing through a half-wave plate followed by a polarizer is a single qubit quantum computer. Is this a correct description? If yes, what exactly we are computing? 2. Why the light beams of H and V polarization are 'entangled'? 3. If we repeat the same experiment using radio waves, is it still a quantum computer?

Can you provide me model no. of your torch? OR link? I tried to buy some of these it doesn't provide pointed single source instead it is like toy providing dancing lights.

First!

Alice is Raj Kuthrappali's sister from Big Bang Theory. ;-)

Love to see brilliant young people on YT. Thanks! BTW, this video took _a lot_ of work. Thanks for that, too.

"Q-Cardiac"? Almost... I don't think I've still seen the ladybugs move, yet. Great though, for as far as it does go. Fingers crossed for the next. Thanks!

Ali...........the secret is time...... meaning warping time.........the one way..........black hole.......space n time becomes constant in our eyes or perspective..... however........in the other end.......well....... imagination is beyond your comprehensive human mind.......fyi........you're simply amazing btw 😊

"Why does light move slower through glass than Through a vacuum?" Not that difficult to explain. First you must understand what a magnetic field is. It is a toroid of field energy. A vortex that feeds in on itself in other words. Well, that is what every atom in the glass (or Crystal) IS. A magnetic field. So it is not that the speed of the light changes, it doesn't, the speed of the light remains constant. What is happening inside the glass is the light is moving FURTHER, because instead of going in a straight line, it is zig zagging around all the vortexes of energy. A zig zag is further than a straight line, thereby causing the light to appear slower while actually not slowing down at all.

I am from your future. You know it does, and much like myself, the answer gives a bit of a headache. PS: I like your system. Your explanations are cool. Even better when everything works better than expected.

Congratulations, you made quantum computers sound simple (or at least comprehendible with my monkey brain), and it wasn't done with the hand-wavy magical-sounding oversimplifications that scientific journalists love to use.

I'm trying to understand waves in 3D... Are lightwaves basically 2D in that they oscillate up and down but not on the Z axis? Or do the waves also oscillate "left and right" while also oscillating "up and down"? Do the waves have a thickness?

Did you _actually_ shine a laser into your own eye?! Don't know whether that piece was hilarious or terrifying! On a more serious note, the explanation of polarising polymer starting at 14:40 didn't sound quite right. Wouldn't it be the more mobile electrons that are instrumental in transmitting the light, not the ones that are locked in place? In your previous videos on refraction (and 3b1b's related ones) the transmission of light is explained as a sympathetic vibration of electrons resonating in response to the changing E-field produced by light. In the current video you talk about this "using up" the light ... but surely that would depend on whether we get elastic scattering or not? I could be wrong, but it just seemed it should be the opposite way round to how it was explained. Notwithstanding this, fabulous illuminating content, always a joy to watch.

I like these videos. It demonstrates that voyage of discovery in science that is so important for learning science. Note on safety, although I am sure you are using Class 1 laser pointer which are safe without needing protective eyeglasses, people watching this are going to want to repeat the experiments themselves, and if you buy laser pointers from the internet they might say they are Class 1, but in fact be far more powerful. So I think wearing laser protective eye-ware in videos like this would set a good safety example.

I enjoyed the video and love your presenting style but I don't see anything "quantum" going on. Looks like fully explained by classical physics. Entanglement would seem to be another story but it is not involved in this experiment...what am I missing?

Omg, I just found your channel, and I love your content. Your videos are so underrated and deserve more likes!

Recently my engine made me sad, cause i suddenly felt combining horizontal and vertical states are a stupid. Now I think, i think again. ... is this just comparing redundant arrays on hardware level? Nice video!

People may learn more from your useless Quantum computer than will ever be learned from the multi million dollar ones! Personally I'd say yours is likely even better !

really cool stuff! amazing to finally see an example of how quantum computers work, the usuall pop-science and sort of hand-wavy way of explaining doesn't really makes it any clearer. good effort!