The Insane Mechanism of a Quantum Computer?
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- Опубликовано: 9 июн 2024
- (To study Quantum Computing in depth, go to: brilliant.org/arvinash -- you can sign up for free! And the first 200 people will get 20% off their annual membership. The Brilliant course, "Quantum Computing" is one of the best offered online today! Enjoy!
Chapters:
0:00 - Quantum Computers
0:55 - Common computer components
2:51 - What is a Transistor?
3:20 - What is a qubit?
6:07 - Advantages of superpositions
6:40 - How does a quantum computer compute?
7:30 - Quantum algorithms
8:54 - What kinds of problems can Q computers solve?
10:32 - Why are quantum computers difficult to build?
11:50 - Is the universe a giant computer?
Summary:
(This is part 1 or at least a 2 part series on quantum computing. Each video will be successively more in-depth.) Classical and quantum computers share many general components - power supply, data storage, RAM memory, motherboard, but they differ in the way the central processing unit (CPU) works. A classical CPU is made from transistors, which is like an on/off switch. If it is on, then it’s like the number 1 or true. If it is off it’s like the number 0 or false. This is what binary means. A transitor represents a binary bit.
Quantum computers do not use binary bits, they use quantum bits or qubits. What is a Qubit? It is a bit in a superposition of 1 and 0. What does superposition mean? Quantum theory shows that quantum objects such as electrons, prior to measurement, are in multiple states at the same time. So something like the spin of an electron, which is a measurement of its intrinsic angular momentum, when measured is either up or down. When not measured, it is in both states of up and down. This is what superposition is.
If you visualize a qubit as a sphere, a classical bit can be 1 or 0 - the north pole or south pole. But a qubit can be in any place on the surface of this sphere depending on the superposition. A single qubit can be any mixture of 1 and 0, so the possible values are infinite! So whereas the classical binary bit can only take one of two values, the superposition allows a qubit to take on a potentially infinite number of values.
A qubit can be created by any quantum object like photons, electrons or even atoms. It doesn’t really matter. It just needs to be a quantum object in superposition. Qubits allow us to ask several questions at once during computation, “what is the result if the qubit is one? What is the result if the qubit is zero? What is the result if it is anything in between?”-- thus we can calculate the process where the bit is both zero and one and anything in between.
This downside is that the result of the computation will also be in superposition. This means that the quantum computers needs to maintain superposition throughout the process. The inputs AND outputs are both in superposition. The quantum computer operates WITHOUT any measurement of any kind. Because there are no measurements, the computer state evolves according to quantum mechanics.
The computer follows multiple computational paths at the same time, analogous to the way a photon could follow multiple paths through a double slit experiment. It only has a certain probability of ending up on certain locations.
However, at the end, there has to be a measurement to get a final result. And this final result from the computer is always classical. It is going to be a one or zero. How do we know whether we should get a one or zero? This is controlled by the quantum algorithm, which are clever programs created by programming scientists that use mathematical tricks to make sure that the probability of getting the correct is answer is as high as it can be.
How do quantum Algorithms work? They word by applying destructive interference on the wrong results, and constructive interference to the correct results. It does a kind of interference experiment to find the most likely answer.
So how is this so much more powerful than classical computers for solving problems? The quantum computer doesn’t do the usual stuff in a faster way. It doesn’t calculate all the possible results very quickly. It calculates all functions for all inputs at once. It calculates multiple functions at once for multiple possible inputs.
#quantumcomputer
Why is it hard to build quantum computers?
Qubits have to be isolated from the outside world. They cannot interact with any molecules or photons or other particles. This requires extreme cooling, because heat can modify or destroy the superposition by interacting with Qubits. So, this is why quantum computers are cooled to near absolute zero, that’s -273 degrees Celcius, to effectively eliminate all external thermal energy, so that the superposition is not modified or broken. In addition, Qubits can’t talk to the outside world, but they have to be able to talk to each other very fast. So these connections that the qubits must have with each other is not trivial. 
Наука
Clearest explanation of Quantum Computers I've seen. Great job Arvin.
I've seen way better
But that's only because you are way smarter than everyone else
@@MrBendybruce Thank you!
No doubt at all.
So true 👍. With a little voodoo, everything is clearly understood. 😅
This is the first video that I've seen that doesn't just talk about the hype behind quantum computers or ELI5 qubits, but rather bridges the gap between the two domains (physics and computer science) in a meaningful way.
Check out Scott Aaronson Lex fridman or Sean Carroll
*"What makes a quantum computer fundamentally more powerful?"*
Simple, it has the word 'quantum' in it.
If you order one from Amazon, you only know if you have it when you open the box and look. You might have a dead cat. Or not.
@@bobthedog3337 Your comment is gold lmao
Does it have graphene inside?
Yes makes no sense.
As an electrical engineer for 35 years this is the simplest clearest explanation of a quantum computer I've ever seen amazing job Arvin
AGREED! I've been an EE for 45 years... studied some QM back at school... but this beats Matt, Sabine and many others. Clear, concise... and specifically addresses issues that are commonly misunderstood, and not explained by others. Thanks, Arvin!
@@JR-ng9yo And yet it still seems like he doesn't really explain it fully. He says that since the qubits are in a super position, the computer can check every path in a maze at once, but when you measure the result, the wave collapses and you get a classical answer. But how does it check several paths at once by just casually existing in constant spin? And how does it determine the correct path? I know he said that they use constructive interference to enhance the correct waves, and destructive to cancel out the incorrect ones. But how do you know which ones those are if you don't get an answer until it's all done anyway. I don't get it.
@@soulextracter "how does it check several paths at once"... This is done using "parallelism". Imagine having fifty 8X11 sheets of clear plastic, each with a random number of ink spots on it randomly distributed across it. You are asked to find which single ink spot out of all spots on all 50 sheets is closest to the top right corner of its sheet. You could number all sheets 1-50... use calipers to measure each spot on each sheet to the upper right corner... you could probably simplify by disregarding many dots and only measuring those that look closest... you could keep notes on sheet number and distance... and eventually derive the answer. *OR* you could stack all 50 sheets into a pile... and *look thru all sheets at once* and quickly determine which dot out of all dots on all 50 sheets is closest to its upper right corner! That, my friend, is *PARALLELISM* !
😮😮😮💀💀💀💀💀💀💀💀BRUH I'm also an electrician but I am also a programmer but I completely do not understand it
I asked my friend if I should build a quantum computer and he gave me infinite answers, so I slapped him until he gave me a yes or no answer....
Love it. Seams like it's exactly how it works.
i guess threatening to kill his cat didn't work either?
@Mike Poulin 😂
@@alexejfrohlich5869 only had a 50-50 chance....
😂🤣
*Arvin, your vids keep getting better And BETTER!!* This one answers questions I've had for years that no other vid I've watched addressed (and I've watched A LOT!). You seem to understand where people's misconceptions are. You've also scooped other publishers with the most current news! You have a knack of explaining things clearly and concisely, making your talks the easiest in this field to understand! You ROCK!! Keep it up!!
Fantastic ! 👏 one of the best and simplest explanations of quantum computing I have seen..
This was an Amazing explanation!
You coveted this topic way more in depth than other sources. This is why I love this channel. No matter how much you think you understand something, you always learn something new. Thank you!
Also, the animations were top notch!
This by far the best explanation I've found. Amazing job.
Awesome video/presentation. Can't wait for the next part!
Up until now I may have seen 2 dozen videos about quantum computers on RUclips, and when I saw the notification for this video, I almost skipped it. But Im glad I didn't skip this video because this is the most comprehensive explainer video about quantum computers on RUclips right now. Im kinda shocked you were able to condense all the information in less then a 15 min video
great vid!! can't wait for the follow up!
Awesome as always, can't wait for the next video my friend! If all the educators were like you!
Amazing ! Can’t wait for the next part.
I’ve been away for a bit, but glad to be back. I’ll get caught up on your education. Your a gift and I appreciate your efforts.
This is the first video I will recommend anyone, If they want to know what is quantum computer.
Your explanations are clear and concise.
Great job man! You answered all my questions.
You're one of the best out there Arvin. Love all your videos. Keep going and keep spreading them A1 quality info.
What an explanation. I tried searching some videos but couldn't able to understand that clearly until I saw this. Thank you 😊
Finally a verbal explanation and example of quantum computing that actually makes sense instead of sounding like buzzwords.
Awesome explanation!! Thanks much Arvin.
Very good video. One of the best explanations I've seen.
Very clear explanation!!!!
Thank you, the best explanation I've seen so far!
Great video, very concise explanation!
Excellent! A simple explanation of quantum computing equals understanding. Nice!
Another great video. Thank you Arvin! 😊
I never understood before how quantum computing worked. I finally understood today.. thank you Arvin !!!
Thank you for offering crystal clear views for a starter
This video was a special one, very good way to explain quantum computing using basic principles of QM.
Damn! That was REALLY good! Thank you, Arvin!
I really enjoy watching your episodes. Excellent explanation 👍
Very interactive . Learned a lot from this
In what way was it interactive?
Perfect explanation. Thank you.
Great explanation comes from great understanding.
The first video that focus the importent stuff. Thx. Now i start to understand how it works.
Thank you Arvin. I love your videos!
Many thanks Arvin
Can’t wait to see the next video. Perhaps some applications of quantum computers in the next video may make this topic more clear. What about quantum networks?
Where can we study or specialize in quantum computers? Apparently it’s not covered thoroughly in university’s program of computer science.
Been searching long time for RUclips videos that could explain to me in simple way the difference between a quantum computer against a classical one. Arvin explained it very well. I think the reason why most failed it's because they want to scale up the the understanding of laymen like me to their level, which may never happen, instead of the other way around.
Wow arvin im speechless especially that last bit about the universe.
Q
Thanks Arvin, great video and very clear, and the hat is so gangsta!
Thank you Arvin amazing explanation
Very good explanation with very understandable animation. "A quantum computer takes all possible paths at once". Well done
As usual Arvin Ash provides the best explanations - clear and understandable. I’m just curious about the limits of quantum computation with regard to Grover’s Algorithm. Square root is an amazing improvement for searching data points, but seems like little help with a googol data points or, say, a Graham’s Number of data points.
Hi Arvin, Awesome Video. Better than anything from Google or IBM in trying to explain the gist of a Quantum Computer and that means better than anything out there, period. You covered all the key principles that matter to a holistic understanding. Really props to you !
Much appreciate. Glad it was helpful!
You are the man. Great explanation.
Wow,,. Your explanation is Great 😮
Arv 🔥 you're always blowing my mind
Both classical and quantum computers also need RGB to work
Lol typical female 😉
quantum RGB: any light in between Red, Green, and Blue
@dafuqawew kek
😂 RGB? I think one more color is missing
My favorite physics channel on RUclips
I seriously hope you're working towards explaining shor's algorithm. I've never actually seen a proper explanation of the math behind it, but if anyone can explain that in a way to follow way, it'd be you.
this is mindblowing
Thank you for the video
Great content as always
Great as always
That was an amazing explaination
Output is in superposition. Picking the right option is the trick. This is still at equation stage. Never say impossible!
Excellent presentation of a very esoteric topic.👌
Very well explained.
this topic reminds forgotten analog computers, its interesting that some deprecated technologies not useless in some new researches
Great job 👏
Fu%king out of it as usual !! Thanks Arvin!
Best one I have seen
Brilliantly dumbed-down for consumption. I love this channel!
3:20 the overall graphics were fantastic & intuitive
you blow my mind Arvin
I cannot wait for the cpu video cause I have been wondering about the fundamental processes of a computer for a while now and I can't seem to find much compiled online.
Ooh the ending was just epic😍😍
Hey Arvin Ash such an excellent interesting video that was so well explained! Just a question, what was the music you played at the end or at 13:18 and who's the artist? That music really gives me chills. Or can you send me a link of that music? You've used this spooky music in many of your other videos too.
Well now. That was quite helpful.
This channel is the best on youtube.
great video 🔥🔥
One analogy that I can think of is a quantum computer is sorta like using a large magnet to find the needle in the haystack--The magnet uses it's properties to search the whole stack at once.
That's an interest analogy. Thanks.
That was Brilliant..thanks. The Maze animation explained superposition and measured result best. I'm presuming the hat is to keep your brain in! 👍
Great video
Inspirational bro
Nice! Now the hard part: explaining how the hell you go from qbits to the algorithm
Is my brain a quantum computer? I don't search every phone number I know for the correct owner, I don't search every single face I know to recognize Arvin Ash.
Happy teacher's day from India. You are a great teacher
Arvin… still impress me with your clear explanations. How can a quantum computer determine what is the culprit (“pathogenic protein) of a disease when we evaluate 12K different proteins using proteomics for example? I ask this because I imagine that things get complicated when there are more than one answer. For example different proteins involved.
It would find the most likely answers, provided you have some idea of what the answer should look like.
great vid!
I don't get the explanation of qubits. In classical *analog* computers, a signal can also have values anywhere between 0 and 1, represented by different voltage levels. Surely there must be something more to how qubits work?
1, A classical computer doesn't actually use that in between value. It just counts any voltage below a threshold as 0, and anything above it is a 1; and 2, a quantum computer uses superposition to try every possibility at the same time, while a classical computer has to try one operation at a time
The answers missed the "analog" part of the question so, the difference is that qubits are superimposed sets and friendly to algorithm manipulation, which is what gives it its power.
Indeed. The video did not explain it.
Here is an *actual* explanation.
First, you need to understand the concept of a vector space.
A vector space is a set of things where you can scale them by a number, and add or subtract them. The things in a vector space are called vectors.
There is a more precise way to define vector space, but the precise details are just the things one would expect from making the description I just gave precise.
An example of a vector space is like, the space of triples of 3 numbers, like (x,y,z) , where you can like, say 2.5 * (1,4,2) = (2.5,10,5) , and (2,1,11) + (1,1,1) = (3,2,12) . Another example of a vector space is just "the real numbers".
In quantum mechanics, (or at least one of a couple of mathematically equivalent ways of describing it), the state of a system is always a vector in a certain vector space. This vector space is of a certain kind, called a "Hilbert space".
A Hilbert space is a vector space where you have a concept of the length of a vector, and also a concept of vectors being perpendicular, and the Pythagorean theorem works, and also if you have an infinite sum of vectors which should converge, then there actually is a vector for it to converge to (this last property is something you don't really need to worry about for this explanation).
In quantum mechanics, the vector which describes the current state of a system always has length 1.
An example of this is what he was *trying* to get at when he said that alpha^2 + beta^1 = 1 (though really he should have said that |alpha|^2 + |beta|^2 = 1 in case alpha or beta had an imaginary component)
Now, you need to know what a linear operator (aka linear function aka linear map) is.
Now, a linear combination of a collection of vectors is just a sum of the vectors each multiplied by some number.
For example, 2 * (2,11,2) + 4 * (1,2,3) is an example of a linear combination of (2,11,2) and (1,2,3) . Another example would be 2 * (2,11,2) + 0 * (1,2,3) .
The linear combinations don't have to just be between 2 vectors either, they can have as many as you want. A linear combination of vectors from some vector space, will always be a vector from the same vector space.
[side note : the "dimension" of a vector space is the smallest size a set of vectors from that space can be, such that every vector in that vector space can be expressed as a linear combination of vectors from that set.]
A linear operator is a function which takes input an element of some vector space, and has outputs elements of some vector space (often but not always the space it takes input from, and the space it gives output in, are the same space) such that, it sends linear combinations to corresponding linear combinations, in the sense that,
well, I'll give an example, that will be easier.
If A is a linear operator, then A( 5 * (1,4,2,7) + 2.1 * (1,1,2,2) + 3000 * (4,3,2,1)) = 5 * A((1,4,2,7)) + 2.1 * A((1,1,2,2)) + 3000 * A((4,3,2,1)) .
And, note: A doesn't "know" that its input was in the form of a linear combination of the set of vectors I expressed there,
all the info A gets is the vector (12007.1, 9022.1, 6014.2,3039.2) (which is what that linear combination I wrote evaluates down to. I kind regretting picking not-nice numbers in that example)
Now, in quantum mechanics, basically everything is done using linear operators.
In particular, time evolution, the "given what things are like now, what will they be like in 2 seconds" (or, any given amount of time) is a linear operator.
So, if the computer state is a linear combination of some state and another state, then because time evolution is linear, after the computer does stuff, the computer state ends up being in a corresponding linear combination of what time evolution would do to the corresponding components, and the relative coefficients between them.
Now, suppose that we have some vectors in the Hilbert space for our quantum mechanical system, and let's say these vectors are named, idk, banana, Zamboni, purple, and Sasquatch, and they each have a length of 1.
Suppose that purple and banana are perpendicular, so then (by the Pythagorean theorem ) the lengths of ((1/sqrt(2)) * purple + (1/sqrt(2)) * banana) and ((1/sqrt(2)) * purple - (1/sqrt(2)) * banana) each have a length of 1 (because (1/(sqrt(2))^2 = (1/2) , and (-1/(sqrt(2))^2 = (1/2) , so in both cases we get (1/2) + (1/2) = 1 )
Ah, now there's something I should have probably mentioned earlier (it gets a bit confusing trying to explain just enough linear algebra to explain quantum mechanics while simultaneously explaining the quantum mechanics) : measurement!
When there is a discrete set of possible measurement outcomes, we can associate with each one, a component of the state. For each possible outcome, there is a linear operator (a projection operator, as it happens) which sends any state to a component of that state which corresponds to that measurement outcome, and if you add up the components that these different operators give of the original state, they add up to the original state,
and furthermore, each of these components are perpendicular to each of the other components.
The square of the length of each of these components corresponds to the probability of measuring that outcome. That these add up to 1 represents the fact that "definitely there is something that happens", and also that this is by adding up squares of lengths of perpendicular things, is because of the Pythagorean theorem again.
So, if there is a measurement we are doing which has possible outcomes "purple" and "banana", then, well, I named these measurement outcomes after the vectors I used before, so I hope it isn't too much of a surprise that I want the "banana" component of ((1/sqrt(2)) * purple + (1/sqrt(2)) * banana) to be (1/sqrt(2)) * banana ,
and the "banana" component of ((1/sqrt(2)) * purple - (1/sqrt(2)) * banana) to be (-1/sqrt(2)) * banana .
Note the minus sign!
But, in both cases, if we take the square of the length of the "the observed outcome is banana" component, in both cases, we get (1/2) (if instead of (-1/sqrt(2)) we instead had like, (sqrt(-1)/sqrt(2)) , well, technically we would multiply it by its complex conjugate, which is (-sqrt(-1)/sqrt(2)), and so the product would still end up being (1/2), but you can also just think of it as "we take the absolute value before we square it." But also, I'm getting into unnecessary details, you don't have to worry about this part.). (similarly a (1/2) chance of "purple" in both cases, but I showed "banana" to demonstrate what happens with the minus sign).
Ok, now, suppose that the time evolution operator U, which sends a state to what the state would be after (say) 3 seconds,
suppose it sends Sasquatch to ((1/sqrt(2)) * purple + (1/sqrt(2)) * banana) ,
and suppose it sends Zamboni to ((1/sqrt(2)) * purple - (1/sqrt(2)) * banana) .
Because U is linear, it will send (1/(sqrt(2))) * Sasquatch + (1/(sqrt(2))) * Zamboni to
(1/(sqrt(2))) * ((1/sqrt(2)) * purple + (1/sqrt(2)) * banana) + (1/(sqrt(2))) * ((1/sqrt(2)) * purple - (1/sqrt(2)) * banana)
which simplifies down to (1/2) * purple + (1/2) * banana + (1/2) * purple - (1/2) * banana = purple .
While, on the other hand, it will send
(1/(sqrt(2))) * Sasquatch - (1/(sqrt(2))) * Zamboni
(note the minus sign!)
to (1/(sqrt(2))) * ((1/sqrt(2)) * purple + (1/sqrt(2)) * banana) - (1/(sqrt(2))) * ((1/sqrt(2)) * purple - (1/sqrt(2)) * banana)
which simplifies down to
(1/2) * purple + (1/2) * banana - (1/2) * purple + (1/2) * banana = banana .
This is the sort of thing that he is talking about when he talks about the positive and negative interference.
Sasquatch and Zamboni would each individually produce a superposition of purple and banana (two different superpositions, but if one measures whether banana or purple, the probabilities would be the same, though if one measured a different question the two could be distinguishable), but different linear combinations of Sasquatch and Zamboni result in either the purple components having negative interference and canceling out while the banana components have positive interference and become more likely, or visa versa, depending on which linear combination of Sasquatch and Zamboni is used.
Ok, it is midnight, I probably shouldn't have taken the time to write all this on a youtube comment? But, if you have any further questions, let me know.
@@drdca8263 you could've linked to a wikipedia article. A youtube comment can't hope to ever be very well formatted
@@drdca8263 Mr. Zamboni, do you take credit card or paypal? great stuff +1
I loved this explanation. Also understood how the parts of the computer interact with each other better here. Wasn't expecting it to end with the universe is a simulation theory, but it kinda does make sense to end with here.
Note that there is a significant difference between a "computational universe" and "simulation theory" whiich he left ambiguous as it can apply to both.
A simulation theory requires a physical computer outside the simulated universe but a computational universe is one where the computation is the fundamental bit not built on top of anything but past computations acting on some network array of past logic operations. It is a bit conceptually strange to think of as historically we have always thought of a computer as a physical object performing an operation but in a computational universe the computations are the fundamental building blocks from which familiar properties like space, energy momentum etc. emerge. So rather than a physical computer simulating a system you are more or less projecting a piece of the underlying computational reality which acts as the fundamental building blocks of the universe. That is to say in the computational universe paradigm if the underlying computational simulation is sufficiently accurate i.e. has the right algorithm running on the right network then there is fundamentally no difference between the simulation and the and the simulating universe aside for the snapshot in time. i.e. the simulation is really an observation of the past in such a precise scenario. The catch of course is that the rate of times passage would be identical between the simulating universe and all the simulations so you could only know if you got the right network and algorithm for sure after running the simulation for 13.8 billion years. Other algorithms and starting networks wouldn't be wrong per say they would just show you a different snapshot of the computational universe in essence what is conventionally the "multiverse".
Additionally in this paradigm the question of whether math is discovered or invented is rendered trivial as an observation is a frame or reference in space and time and a measurement is a type of acceleration in the space of all possible outcomes of the wavefunction with the observation being a single projection of that higher dimensional object in a lower number of dimensions.
It is a very trippy paradigm that is really hard to grasp in fact it is probably fundamentally impossible for the whole system to be represented by our puny brains.
Yes, I agree this is the best video on quantum computers but still didn't explain how to do the computations. I hope it's in next teaser video
Make two separate videos on entropy in thermodynamics and in information theory.....
quite excited for new video about LOGIC GATES!!!!
Great stuff
Interesting stuff. I'm still waiting for a quantum Etch-A-Sketch. Fun for the whole family!
Fun for every family at once (!)
@@jeffreyspinner9213 😁😆👍
I want more video related to this topic
I always want to how computers works in detail
Can you make a full series about Classical and Quantum computer
regarding classical computer, check out the "crash course computer science". it explains everything about how classical computer works and is awesomely fun to watch :)
ruclips.net/video/tpIctyqH29Q/видео.html
Fission and fusion too. Maintaining a constant fusion reaction for constant power source. Small steps of progress. Bits and Q-bits...
Good job on the quantum computer explanation! In terms of the universe being a computation which processes existence: Have you come across Stephen Wolfram's theory of the computational hypergraph of reality?
Very good
Thank you, Arvin, but how the number of iterations is reduced by the square root of the classical one? Something is missing here!
Only using the Grover algorithm. There are other algorithms that work differently.
@@ArvinAsh You could have provided at elast one example. The fundamental element of a quantum computer is not the qubit, but how an algorithm is applied. And this part, the only part that gives a quantum computer a meaning you totally left out.
I just fall in love with this channel and i just watch only 2 videos only few people are capable of doing such kind of magic to attract people to himself love from pakistan
In classical computers there are electronic circuits like adders, multipliers etc. that perform the actual computation -- produce outputs from inputs according to some rules.
What are the substitutes for the circuits in quantum computer that, say, produce the sum of two numbers?
Thank you is not enough to express my gratitude. Alas, thank you is what i can come up with 😇
Because of this video, i can now build my own quantum computer.
Hey Arvin Ash
You're doing an amazing job. Can you explain what's a Time crystal ?
Guess i have to wait for the next video to understand this.
thank you