Quantum Computing 'Magic' - Computerphile
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- čas přidán 10. 11. 2016
- Quantum Computing offers a potential sea-change in computer power, but what are the issues with it, why aren't we all using quantum iphones already? Associate Professor Dr Thorsten Altenkirch.
Link to more information & Quantum IO Monad Code: bit.ly/Computerphile_QIOMonad
*From Thorsten: "We have updated the hackage package to work with the new monad library. If you want to play with QIO read the paper and download the code and then you can start quantum programming. :-)"
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This video was filmed and edited by Sean Riley.
Computer Science at the University of Nottingham: bit.ly/nottscomputer
Computerphile is a sister project to Brady Haran's Numberphile. More at www.bradyharan.com
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This speaker is fantastic. A wonderful voice for explanation, and always extremely precise in what he says. Everything I hear him say is what Descartes would have called a "clear and distinct idea".
Regardless of the scientific content, is it just me, or does he seem like a super-likeable person??
"As soon as you look at them." Really... really we should all start at remembering to change that to "as soon as they *interact with something*" as people keep getting "look" muddled up with "person looks" instead of "anything bumps into them". :P
TechyBen Finally, I was getting confused
Well, I see lots of newspapers report it that way. So hopefully less those informed, and more the problem of the media.
Listen to this fella, people
Precisely. The last thing we need is more anthropocentrism.
But when something "bumps into them", couldn't they just become entangled as well?
More quantum computing videos! Love them.
Dunno if i'll be able to watch them or not...
You missed the Quantum physics joke. That it can be either way until you check the state.
***** i'm not in the us.
TheRealNaxos seconded
what a horrible joke
Talks intelligently about quantum computing; Writes shor's algorithm in Haskell. I feel that THIS is someone worth listing to about quantum computing.
People think that Haskell is a language designed for geniuses or something like that, while it just uses a different programming paradigm. If you start programming with a functional programming language you are not worse of, since there is nothing intrinsically difficult about functional programming.
Of course, coming from a imperative background, it might be hard to switch to Haskell or LISP or what have you not, but that can be said the other way around. And I think that is the reason the myth of Haskell being a difficult language originated from: People with imperative programming background being overwhelmed by a different paradigm.
if hes helping you so much, where is your quantum computer then? you didnt get helped that much.
I am going to help you immensely by tucking you in and giving you a glass of warm milk so you can sleep soundly 💤
Hands down the best explanation I have yet heard. Thank you for making the extremely complex understandable.
from what ive learned over the years, its all simpler than you think. lots of scientists and groups obscure the rational with an overly complex explanation for the sake of making it seem more wonderful and magical than it is when in reality its just common sense in the end. Theres just so much misunderstanding around these topics its not even funny. and honestly im going to put my tin foil hat on and claim that its done on purpose to keep these things exclusive for marketing reasons. like Computer UIs and interactivity getting so overly simplified that the average person has no idea how computers work any more. its all for the sake of marketing. the less informed you are about how things work the more i can take advantage of you.
Dr Thorsten Altenkirch? Neat! Can we get some insights into functional programming and Type Theory now? :)
you probably know enough already about it. :p
Marius Wegner I don't actually have any kind of formal education in these subjects and only slowly learned about various parts of this. I'm still far from any kind of deep understanding.
However, even if, as is likely the case, Computerphile won't go into the details about these topics that I'd actually seek, it's a beautiful topic and one that'd probably be of interest to plenty of Computerphile watchers.
Artem Borisovskiy Monads really are like burritos :o)
Artem Borisovskiy you have a point. computerphile should make one video about functional programming or monads in general. type theory is still kinda hard and not as practical as one might think.
Marius Wegner not as practical as one might think? How so?
one of the best explanations of it ever
why cant the guy hold a camera? or use a tripod? or do some stabilization?
Thank you. And all the rapid, unnecessary zooms. Really distracting. I love the content, but the camerawork, well, needs work. Or yeah... a friggin tripod. C'mon...
Damn you I read this comment half way through the video, didnt even notice the shaking before, now its making me nauseous.
Thanks, finally a video about Quantum computing that actually provides information (&links!) about the algorithms, not just the qubits :)
I love this area of scientific discovery and exploration. I'm confident we'll both find and not find the answers for which we are looking.
I'm studying Computer Scienece at Nottingham University next year, Can't wait!
Please make more Quantum Computing videos, its so hard to find good videos from real professors on the topic.
Cool, more on the simulated quantum computer library would be nice!
This reminds me of the old Far Side comic where some cows are standing around on two legs talking in a field. Then one says "car!" and they are all on all fours eating grass as the car drives by.
More of this topic. Can't get enough.
Oh shat dschörman äckzent, I laik it
This guy is so german :D
WannaBeMLG Ya!
Good video, I really liked his explanation.
I find it interesting, though, that everyone that talks about quantum mechanics tend to choose the interpretation that they like and then tend to talk like that's either the only one or downplay all the others. Most people I've heard talk about the heisenberg interpretation and down play many worlds theory, and this week I heard a completely different "riding-wave" theory. The fact is that there is still too much we don't know, and I think that's presents the biggest reason why simulating a quantum system in a classical system is hard. There might be that "unknown law" that he talks about, and without that "unknown law" I don't see how a classical simulation could be judged as accurate.
Very interesting video! It really helped me in my understanding of quantum computing.
Hoped you've had mentioned the IBM project. They offer a kind of quantum language, a visualisation of said language (actually the process can be done both ways), a great tutorial on quantum algorithms and programming, simulated results and for the most important part: They schedule your program upon demand on an available processing slot on their actual 5qubit processor. It's free to study and can easily sign up using your IBM, Google or Github account.
He has to be german
No scheiße Sherlock !
Quantum Computing. Das ist gut!
He is, he's a Professor of Computer Science at Nottingham Uni :)
no he's obviously not german , he's Professor Dr Thorsten Altenkirch
Hi might be Austrian or even Swizz.... (but i highly doubt the last alternative)
Thank you so much for this video. The best explanation is this because he is know this staff! he does not read from a script! It is easy for him and makes it easy for us to understand!
It should be noted (and the video doesn't put enough emphasis on this imo), that quantum computing would be extremely faster than classical computing *ONLY FOR CERTAIN PROBLEMS*. A quantum computer wouldn't be faster for playing video games or browsing the web, it would probably be even slower.
Yea, I see this misunderstanding pretty frequently when people talk about quantum computers. I think when people hear "quantum computers would break RSA" the assumption is "quantum computers are REALLY FRIGGIN FAST". Seems they think it's just a matter increasing the processing speed rather than enabling us to reduce the actual computational complexity of the problem itself. It's a reasonable misunderstanding, and that makes it all the more important that science journalists really drive that point home when talking about it.
there are quantum algorithms for finding items in lists, something regularly used in programs, so yes, they could speed up your applications.
Nathan Dehnel looking something up in a list is already O(log(n)). Furthermore, for most applications, n stays in the range of millions (or fewer). A faster lookup wouldn't be meaningful for general computing. This would be like saying "we have a super fast way to crack eggs so now we can bake a cake in half the time"
Tim Huff Depends whether the data is sorted or not.
Nathan Dehnel yea, but sorting itself is O(nlog(n)) and only needs to be done once (if at all - maintaining a sorted list is cheap). The point is, you could make all lookups instantaneous and it wouldn't have a meaningful impact on general application speed
I thought "Is he German?"
Then I looked at his name, which made me happy :)
His accent is really strong though
I still like him :)
(I am German)
Same here loö
Dae4ever I read "Than I..." and I thought you were native English, because in one's native language, people often don't think about grammar anymore, but then you wrote you're German as well :$ Anyway, it should be "Then". "Than" is used to compare stuff. "Then" to state an order in which things happen(ed).
(I am Dutch)
Oh yeah, thank u :)
Dae4ever Gerne ;)
I either 45% or 80% understood the contents of this video.
I understood it I used magic!
Or, both 40% AND 80%, as long as you don't look within to decipher which amount of understanding you really have! :-P
I watched you while you were watching the video. You actually only 45% understood this video.
@@crazyspace3913 In my observation, he understood 80%
You mean you either full or not at all understood the contents of this video, and sometimes both at the same time.
more content from this dude, he is a pleasure to watch.
Debugging a quantum computer cannot be fun...
Well, we already have code that sometimes works and sometimes doesn't, and that is so complicated and spaghettified as to be basically a black box, so how can it get any worse?
that analogy doesn't work, you can debug classical computing programs, it's just really really hard, not impossible. quantum seems like it's not possible to fully debug since you can't look at the state.
You can look at the last state but for resmung you have to run the program all over again.
well isn't the art then, to write the program in such a way that it makes use of this ever changing state? I mean that's why we want quantum computers in the first place, to have unsolvable encryption
You cannot observe the internal state without destroying the quantum-interactions that the quantum computation is based on. You might be able to deliberately interact with the system in some ways that would give you some hint about how the system is configured, but that is about it. No single-stepping through quantum code I'm afraid.
I do love to get my mind fried ~ great vid guys.
Epic explanation. Love that guy!
it's our boy, Altenkirch!
I was just getting ready to ask if it could be simulated at the end but you beat me to it!
Can you make video about DNA Computer ?
Very informative especially the idea that if you look at qbits they behave like particles instead of waves.
All this quantum stuff looks like optimizations someone did to the supercomputer that runs the simulation of our universe.
can you explain how discription code language works ? like transfering the zeros and ones to the coding languages
Nice video!
How about one about photonic computing next?
Best Accent Ever! :D :D great explanation too. I understood the ideas conveyed here quite well! Thanks Gents.
great explanation, great accent :3
Quantum Physics: Getting Trolled by Nature
Is the multiplication in a Quantum Computers (power?) relative to a Qubits superposition scale?
Cool, keep on the good work
does anyone have a link to information on nondestructive measurement of photons and its effects on quantum interference?
My intuition is perfect!
Ya?
Videos such as this always seem to avoid the mechanics of how a quantum computer 'runs a program'. Is there a conventional set of instructions which get passed through the qbits as though they were acting as a conventional register or is it more like the qbits are running along side a conventional processor that makes calls to it, like grabbing a random number from a RdRand?
Steve Gould This is the process:
1. you setup the qbits, some will be 1 or 0, some will be in a superposition ex 20:80 superposition.
2. you do quantum operations, ex multiplication, adition. These will change the states of the qbits.
(ex. if you do multiplication of two 1qbit numbers 20:80 and 40:60 you would get 30:70, its basically operation with probabilities)
once you do the quantum operations, you have qbits in specific states, some are 1s other are 0s, and many are inbetweens like 70:30 chance etc. (If you measure it now, you will get random values for the inbetween bits with 70% chance of 1 and 30% chance of 0) so far you have an unreliable computer that gives you the correct answer some % of the time, and its no more efficient than a normal computer.
3. you do amplitude amplification, this is the quantum magic part. this is where you get the efficiency. this takes the 70:30 and multiplies it with itself, so it will become either 97:3 or 49:51 depending on what way you need the multiplication to go(algorithm decided this), you repeat this 5-10 times and you get something like 1 in trilion chance of getting the wrong result.
4. Now that the randomness is killed, you measure the qbits and verify the result on a normal computer.
Thanks Man !!
This explains a lot
Thanks I finally have some basic understand of how we measure the qubits after using them. I suspected we took several measurement of the same system to get and "average"
Well, in most cases once you have an answer it's easy to test whether it is correct or not, so even if you get unlucky and hit the one in a hundred false result, you can easily check. Think of factoring number: it is easy to check whether a given number is a factor of another given number: you just divide and check if you get an integer.
WoWOmegor The amplitude amplification part is key. Without that part you have nothing. You have no way of extracting more information than a random guess.
Even if you took average values 1000s of times, it will be the same as if a normal computer tried 1000 posibilities, just in random order.
So quantum computing is a little like cold fusion? Functional in a perfect system, just impossible to engineer?
Yes, with the difference being that we can never know if the perfect system we have in mind would ever actually work, because we're never allowed to look at how it works.
Imagine trying to make a clock, but every time you try to check if the hands are moving at the right speeds, the clock always stops working.
We have to come up with a design that's so perfect that we can know it works without ever checking, which if you've ever written code, you'll know is a miracle...
So far, we don't know. We have to scale it up to find out. So unlike Cold Fusion, which currently goes against known observations, a large scale Quantum Computer has not yet been tested to know either way.
So far observations of quantum systems in general have found no upper size limit... but only got to the size of a small grain of diamond as far as I know.
Also pretty sure we have been building actual cold fusion reactors. They might not be efficient, but they *are* cold fusion reactors. :)
Don't say cold fusion is impossible to engineer. At the moment there are several groups around getting interesting results. While it's certainly not trivial, it doesn't seem to be impossible.
well you could listen to the ticks of the clock, but theres a chance this analogy doesnt extend that far and still apply to quantum stuff, if you get what im trying to say
sir thanks for the info,am new to quantum computing, since quantum computer is like shrodinger's cat, ie, info is can be 0 and 1 at the same time, sir is linear algebra still very much applicable there, because classical computers use the laws of linear algebra (de morgan's law,..........) to minumix their circuits ,which are just the properties of vectorspace in linear algebra.thanks
Quantum computing is incredibly interesting. I feel like it's one of the first things physicists simulate after learning some (advanced) quantum.
I've recently heard about the Pilot Wave Theory. Should take a look into it.
It's from 1927
Thanks for the sub! :D
you show something on the whiteboard, s it must be asked. WHAT DOES IT MEAN?
It seems to me that to crack quantum computing we would be directly harnessing the raw processing power of the computer in which our universe simulation is running, and I suspect the programmer(s) may have made it very hard to crack! :)
I have a one question professor
Can quantum computer compute next week lottery numbers,
I want to use it for my evil plans
Is there a followup to this video now that the D-WAVE is finished?
His such a geek! I love it!
They recently took the first ever photo of light behaving both as a wave and a particle! You should do a video on that.
phys(.)org/news/2015-03-particle.html (delete the parenthesis)
If I could trouble the better-informed on quantum mechanics with a question: I understand that the act of observing a quantum system causes the superposition property to essentially be lost (Is this waveform collapse? Decoherence? Resolution? I'm still learning the terminology)--the wave now behaves like a particle. What does it mean to "observe" a quantum system in these scenarios? What specific actions are taken upon quantum system? I saw from IBM's videos on the topic and it was explained that (in their systems, at least) microwave pulses apply constructive interference that change qubit state as well as entangle two or more qubits. Is something similar happening in order to measure/observe the quantum system?
Please feel free to correct anything I may have gotten wrong. :-)
This guy might be my favorite person of all time. Chomsky? Russell? Scrubs. Give me some of that Altenkirch.
so you are saying all of my print statements littering my code for error checking are not going to be forward compatible in quantum computing.
Inspected the CSS on that Quantum IO Monad page. It's screaming at me.
I like the honesty to say that it is unknown whether there are any fundamental obstructions against creating large scale coherent quantum systems. It might be there is some such thing, maybe of statistic nature similarly to the second law of thermodynamics. If say it were to require, in order to prevent de-coherence, an energy that grows proportional to the exponentially increasing number of superposed states in large systems, then that would probably put any practical application beyond our grasp. But I think there is vastly more effort invested on the assumption that quantum computation will turn out to be feasible than to research the possibility of a fundamental obstruction against it.
A particle surrounded by a wave. The wave of the particle going trough the double slit creates an interference pattern and the particle follows it randomly. Trying to "see or measure" it disrupt the wave and the particle acts as a particle.
What about the no-teleportation theorem? Quantum state cannot be converted into classical bits. So, what does this say for your classical simulation of a quantum computer if you cannot convert quantum state into classical bits?
the idea is you collapse the states into either 1 or 0 (the classical bits) by measuring it.
If a qbit and an observer are in a closed box, and we are outside the box. Is the Qbit in a superposition to us if the observer in the box observes it?
no. as soon as the cubit interacts with something it loses its superposition
Quanzum compuzing...love it
May I put to the person in the video and idea that I have had. At the beginning he talks about how particles move in the duble slit experiment. He talks about how they behave like waves but as soon as you put detectors on the slits they behave like particles. My thought is what if the wave like behaviour is in fact a manifestation of the way Space/Time is effected by the movement of the particle. So in fact when we observe the wave like effects what we are seeing is space/time moving like water moves when a boat moves though it.
Is this and interesting thought?
excellent!
Can computerphile do a type theory episode with Thorsten?
why am I so fasinated with this man.....
Now do one on homotopy type theory!
i think it is not about 'looking' but about measure, which by definition changes state of a particle superposition.
Is all this information still pretty much up to date?
So if quantum computing on larger scale is made to work will internet security as it is now be permanently broken?
I would say an emphatic YES to that! The most sophisticated encryption algorithms in use today use the product of multi-digit (large) prime numbers, which while easy to use during the encryption process, are exceedingly difficult to determine from the resulting encryption(s). "Factoring" out the primes from the result is next to impossible using linear classical (or even parallel classical) computation methods. It simply takes too damn long! The use of parallel quantum machines to perform these tasks would move the breaking of these encryptions from the realm of the "next to impossible" into the "not that hard in a not-too-excessive period of time" realm; thus, there goes online banking (to name just one of the many casualties...). These machines are exceedingly scary to imagine at the present time!!!
I'm truly hoping that the "scalability" problem will be this technologies downfall, at least until we have devised new methods for protecting our data that don't fall prey so easily to it...
The alternative will be like being "knocked back to the stone age"!
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Wow, physics I don't intuitively understand, that's quite scary to tell the truth.
This is pretty cool overall, I just hope whoever gets this power uses it responsibly.
Sät Denglisch sough!
I don't have all the computations but I can predict precisely!
The double slit becomes interpretable as soon as you start to think about it as „at which slit did the electron not bump into other particles?“
The obvious answer is: both!
If the pilot-wave theory is right then what would that mean for the future of quantum computing ?
Nothing different. Pilot wave theory still allows quantum superposition and entanglement.
Is it possible to get a 'real' random number with a quantum processor? So, not like the current pseudo rand() in c c++ java...
Yes. In fact, if all you want to do is generating random numbers you can already by such processors.
Why would you want that though...?
Cryptography mostly
Perfectionism/idealism
Currently the quantum process of radioactive decay is used to generate truly random numbers
Finally a quantumn computer video
funny that you talk about quantum computing and there's the second degree polynomial formula on the whiteboard :p. one would hope scientists of this caliber know these by heart haha.
Yes, but even we scientists may do A-level maths with their son in their office. :-)
We could have cracked this during lockdown. There were 1000s of home working computers that were on from 9-5 and completely unobserved. 😉
We really need CC on this guys.
avts I wish all science videos had CC, it makes it easy for translators. That said ze English of ze German zientist iz fine. It's a cute accent!
Is there a quantum computer that doesn't use superconductivity? Why current ones need it?
Superconductivity is one of the ways you can create a coherent quantum state (i.e. a quantum state which can be sustained for long enough without collapsing).
Indeed, a super-current is less sensitive to internal sources of perturbation (i.e. sources of decoherence) since the electrons encounter nearly no scattering events (at low temperature).
Thus, this super-current can be used as a qubit's quantum state.
However, this is not the only way one could create a coherent quantum state. You could also possibly use the spin of the electron, the polarization of a photon, etc.
And yes, many research teams also work on these approaches, which are equally valid, as far as we can tell.
I wonder how it's possible to not interact with a particle if there is gravity. Gravity might be extremely insignificant on this mass to distance ratio but it's shouldn't ever be absolute zero between any two particles with mass, right? How is it that gravity isn't collapsing every wave function?
Beware! You're trying to blend gravity and quantum mechanics together :)
The question of knowing if gravity should be considered as an interaction (in the particle physics way) is not settled yet, as no "gravity boson" or "gravity quantum field" as been proven to exist.
Thanks for the answer. With "gravity quantum field" you mean like "regular gravity on smaller scale"? I always thought gravity is just so insignificant for QM, not that something else entirely is needed because QM actually violates it.
schrodinger's bit
i mean, i thought we had generally settled on the pilot wave interpretation of quantum behavior?
you know, a particle sending waves ahead of itself and interfering with itself as it moves around the world, those waves being the fluctuations in the electron field, therefore, its both a wave and a particle because the particle causes the wave.
Something is still written in Pascal? That brings back memories! My view is that the magical ability of quantum computing to instantly solve O(2^n) problems is of itself the proof that ultimately the universe *is* classical at the large scale and that such solutions are impossible. The double-slit experiment itself is proof that you can't fool the universe, and you can't fool it into accidentally cracking the ultimate hard task in mathematics.
haskell language
We shouldn't look at them while they are computing the answer. Then how do we make sure the answer is correct? how do we make sure it isn't rubbish? does anybody knows how do those qubits "computes" the answer?
Really enjoyed, I wouldn't appose to some subtitles though, just saying.
Nice video, although I still cannot wrap my head around how a qubit knows if it is being observed or not
There is a lot of baggage that comes with the word "observe". Generally when people hear that word they think that a conscious observer is necessary, when in reality decoherence happens whenever you have an interaction of two sufficiently large quantum systems. Like the professor said, it's not known exactly how big a system can be before it stops exhibiting quantum behaviour and starts acting classical, or if that's even the right question to ask, but no "observer" is necessary.
that dude is awesome
This dude is clever.
Quantum Hackers..... one day...
Não.
Use quantum computers to decrypt important government stuff
I thought IBM was working on a prototype quantum machine.... OS and all. Has this changed?
Source?
You missed the point. It isn't about whether it's possible to have qubits, it's about whether it's possible to build a system that's actually a functional computer that can accomplish meaningful things.
if they had the technology to build the complexity of an OS, they would be able to break into any system protected by RSA :P
The Real Maxis Google. Actually, I think they've built or bought some, too.
Amen amen amen
pebble smart watch.... nice...
A qubit has a variable amplitude somewhere between your elbow and the tip of your finger.
I think analog computation and neural networks would be useful in this context. if the answer is either 3 or 5 that means that this computer computes chances of things happening. the result is like 'im 20% sure X is the answer and im sure 80% sure Y is the answer.' thats kinda what a neural network gives an an answer.