Quantum Supremacy Explained

Quantum Supremacy Explained


Quantum supremacy’s that moment when a quantum
computer beats the best supercomputers at solving some kind of problem, and it’s a
very exciting time right now in quantum computing because, as of recording this video we’re
on the brink of having quantum supremacy, maybe it’s already happened. So I’m going to explain what quantum supremacy
is and why it is so exciting. So to explain quantum supremacy it’s worth
me explaining how quantum computers work. Us physicists, we call normal computers ‘classical’
computers, and classical computers work with binary. There’s loads of bits that can either be
in a state of zero or one. In a quantum computer you have quantum bits,
qubits, which can be in the state zero, or one, or they can be in a special intermediate
state and that’s called a superposition. It’s a special phenomenon in quantum physics
that quantum computers take advantage of. Now when you measure a qubit the result you
get is based on a probability, so if you set this superposition state to be in the middle,
you’ve got a 50% chance of getting a zero and a 50% chance of getting a one. But you can tune that state so you can make
it so that you are more likely to get a zero than a one, or the other way around. So that’s the first phenomenon of quantum
physics that quantum computers take advantage of. The second one is called entanglement, and
this is where you bring together several qubits and you join them together, and now that whole
thing has to be treated as one object. So if you take two qubits and you join them
together, now this object can be in the mixed state of four states, so zero zero, zero one,
one zero and one one. Each time you add a new qubit, you double
the number of states that this thing can be in, and that goes up exponentially. So if you want to search through a whole load
of different states, a classical computer has to search through them one by one. But in a quantum computer you’ve got these
special quantum algorithms where you can enhance the probability of the state that you want,
and diminish the probability of it giving you back the state that you don’t want. So those two phenomena: entanglement and superposition
are what give quantum computers their power. So, what kind of quantum computers exist in
the world today? There are a whole bunch of different companies
trying to make a quantum computer: Google, Intel, IBM, Microsoft, D-Wave, amongst others. And to complicate matters, there’s not just
one kind of quantum computer there’s actually a whole load of different approaches. I’ve broken them all down here. An important thing to point out here are Universal
quantum computers. Universal quantum computing can theoretically
simulate any quantum system and so it’s the fundamental computing machinery of the
Universe. There’s other approaches that aren’t Universal
like quantum annealing and ion trap systems. What they’re focused on are solving certain
nice problems better than classical computers by taking advantage of quantum physics and
they’re a valid approach if those kinds of problems are valuable. They can be used as a good stepping stone
towards a Universal quantum computer, because Universal quantum computers are very difficult
to build, and it’s good to learn stuff along the way. I’ve also included the number of qubits
in these quantum computers as of today. Now qubit number is just one measure of how
good a quantum computer is. Just as important is how low the noise is
in the qubits, so how high quality the qubits are, and also how well the qubits are connected
together. So let me describe a bit more about how you’d
do the experiment to prove quantum supremacy. Actually measuring when it has happened is
quite a difficult thing to do. So you take your best quantum computer and
you take your best super computer and you need to give them a problem to solve and then
compare the results. And to begin with the quantum computers can’t
do anything better than a supercomputer except for one thing, and that’s be a quantum computer. Which might sound absurd, but the logic is
this. You can simulate a quantum computer on a classical
computer, but it gets more and more difficult to do so the more qubits you have. Now IBM has got the current record for simulating
a quantum computer with 56 qubits, so people are seeing this as the target, that if you
build a quantum computer with more than 56 qubits, you can’t simulate that with a classical
computer, and so the quantum computer can do some thing better than what a classical
computer can do. So the problem that they are looking at showing
that the quantum computer can beat a classical at is a certain problem called a sampling
problem. Now if you remember back when I was talking
about a qubit being in a superposition state between zero and one that gives you the probability
of which one you’ll get back. Imagine if you’ve got fifty qubits and they
are all entangled together, they are simultaneously in about quadrillion states, that’s a million
billion states at the same time. But when you measure that computer it just
gives you back one state which will just be a bit string of zero, zero, one, zero, one,
one, one, corresponding to each qubit. Now if you keep measuring that computer over
and over again, you’ll get different bit strings back, so different states back, but
over time you’ll build up a distribution of those states, the more likely ones and
the less likely ones, and that’s a probability distribution. And each time you measure the quantum computer
that’s like taking one sample from that probability distribution. Now quantum computers do that completely naturally,
whereas simulating that whole thing on a classical computer is incredibly difficult. So that’s the problem that they are looking
at proving that a quantum computer can do it better than a classical computer. So what’s that problem good for? Absolutely nothing. To begin with. I mean there’s some crossover between this
kind of sampling problem and a sampling problem you get in machine learning. But the shapes of those problems in quantum
computing and machine learning are very ver different, but they come from the same sort
of underlying physics which is called statistical mechanics so there is a tentative overlap
there which people like Google are very very interested in. But I don’t undersell this achievement because,
if you think about it, classical computers have been around for seventy years and they’ve
had literally trillions of dollars worth of money pumped into research and development
to reach them to the incredibly sophisticated machine they are now. Quantum computers have been around for twenty
years-ish, and have had say a hundred million, maybe a billion dollars worth of investment,
for that technology, this new novel technology to come along and beat the classical computers
at even one narrow thing is a, is a huge achievement and that’s only going to progress in the
future and I’m really excited to see how that whole thing evolves. And finally I just want to end with a fact
which I think is incredible. You know I said that you can simulate, using
our best supercomputers, you can simulate a quantum computer with fifty six qubits. Now if you raise the number of qubits up to
two hundred and sixty, the size of the computer you’d need to simulate that would need more
bits then there are atoms in the entire known Universe, which I think is just absolutely
bonkers, but I love it. Thanks so much for watching, that’s all
I’ve got for you today. And thanks also to the sponsor of this video
brilliant.org they’re a website where you learn by doing. And I don’t know about you, when I was at
University I would sit down, I’d write down all the lecture notes, but the time where
I’d really learn the subject was when I sat down and did problems and Brilliant do
a great job of making this fun and slightly addictive, they have a way of framing questions
that I get slightly obsessed with trying to work out the answer to. But that makes it really fun. And they cover a bunch of different subjects:
physics, mathematics, computer science and many more. So if you are interested in checking that
out go to brilliant.org/dos the link’s also in the description below, and otherwise, thank
you for watching again, and I’ll see you on the next video.


99 thoughts on “Quantum Supremacy Explained

  1. The opening sentences makes clear why the whole question is nonsense. He says clearly ‘will be better at SOME problems’. That moment is passed already, I thought, but quantum computers will not be better at ALL problems. In text editing they are quite useless, for instance.

  2. If d7mb a-holes could explain how qubits are used to achieve actual results and the techniques behind them, instead of
    "They are 1 and 0 all the same time"
    Like damn if I used that in my science exams

  3. Bye Bye western civilization. I would've liked to have known you better, but people had to join A.I. with quantum computing. Now we are all slaves for the elites and Zionists.

  4. 0:22 Classical Computers
    • Work with Binary, in bits
    0:42 Quantam
    • Quantam Bits (Q-Bits)
    1:22 Quantam Entanaglement (many Q-Bits)

    2:12 what kind of quantum computers exist today?
    2:37
    • Universal
    • Not Universal

    3:33, How is Quantam Supremacy Measured and Proven?
    • 56 Qubits is what a Quantam Computer can do better than a Supercomputer

    6:13 Statistical Mechanics

    Quantam= Young And New
    Classical = Old and $$$$

  5. Dude, thank you. Your video is the only one have has made real sense to me. Lol no fancy lingo or Bs music all in the back.

  6. What about compute GPUs or GPGPUs? Those have thouands of cores on a single chip making them incredible in parallel processing … What about a super computer with loads of these GPUs?

  7. Wohoo! Google just announced their quantum supremacy result. Turned out I made this video a year and a half too early. Oops!

  8. Maybe Im naive as I work in IT and my interest mainly lay in network engineering. Love the example of qubits, thankyou. It makes so much more sense than other videos trying to exllain this. Secondly, Id like to ask – with the knowledge you have now and Google (the worlds main search engine) keen interest in google home technology and large investment in quantam computing, do you see google becoming somewhat of an end prediction of George Orwell's 1984. Is it possible for these computers to think as an entity or do we program them the same as we program "classical" computers? Also if a quantum computer can always win with a series of qubits that can represent nearly every outcome, what exactly are we going to use this for in everyday life? Do you believe the only true use is to create control in society? Ps. By the "worlds main search engine" I mean, they are meant to be a search engine! Not trying to creep into people's lives with technology that can control and listen to the inner workings of our lives.

  9. To crack a BTC public key takes:

    On Supercomputer:
    500,000,000,000,000,000 years

    On Quantum Superdomputer:
    50,000 years.

    Ye, we fine

  10. Google just announced quantum supremacy so I research what's that, so I am here now. Still don't get it. maybe updated video what google might do with this achievement? Is Next generation Google Pixelbooks and Pixel phones going to be 10x faster than iphone?

  11. So, for any binary "classical computing" computer to simulate any number beyond 56 QubitS require more Physical SIMULATED Qubits than there are atoms in the world? So is this disparity evident?
    The supremacy of Quantum computing is not even quantifiable? It IS this different from binary computing.

  12. I won't consider quantum computers "superior" until they can factor large polynomials faster than a classical computer. Taking the noise spectrum of the quantum computer and using this as the "calculation" to declare "quantum supremacy" is LAME. Just more hype to lure investment into quantum computing companies.

  13. Don't really see the need. Seems (Classical) computers work much better. Binary rules are supreme! If it's a one it's not a zero. Simple is the most reliable.

  14. Ordinarily, I would be super excited about this but Google scares the crap out of me. They have capabilities I can't even imagine and they think they know a better way and they are going to decide what we think and who we elect into office and they're acting pretty smug at the moment meaning they're confident in whatever it is they have cooked up for 2020

  15. So no more encryption! Bummer for everyone. Why do we need it? There is more than of everything and now we hv more and no one knows why.

  16. How do i know IF my socks are clean since they are in the right drawer and i can see them but not SMELL them… But i don't know if they are are from the floor or the washing Machine

  17. idk if i am in the right track, if the quantum computer use to make the decision of an AI to descript the human emotion can it be achieved? or i am at wrong understanding

  18. Thanks verymuch for for explanation .I am 57 but moe or less understood it.Last passed an (indian ie every student passed) )paper in physics in 1984 .Good to feel young again.Thanks

  19. I searched "quantum physics" and watched a TedX where you spoke about quantum physics for 7 year olds. While I was listening I had opened a separate page and scrolled down on a search of "quantum supremacy" and for some reason clicked this vid and it's you. I scrolled past a dozen or so vids and randomly picked this one with no idea this was your channel.

  20. So will quantum computers Use transistors because it would be hard for the superposition to be possible on a transistor

  21. So is it the same thing as comparing a mouse to a computer for their ability to eat cheese and call it mouse supremacy?

  22. The first country to fully dominate quantum computing will break the paradigms of the economy and dominate the stock market. imagine what Russia and China are no longer trying to do right now about it to fulfill your dream of destroy capitalism?

  23. I thought a quantum superposition was the state of some qubit or something existing in one or more places/positions of some domain or such at once? (e.g. such that someone could exist in multiple places via cloning or such) And that quantum entanglement was of how some qubit or something being mutually connected without any direct physical relation or connection, such that they can be related/connected without direct means and be affected as such (e.g. similar to how Leigh, Luke and Ben Solo all eventually affect each other via some means of the force — or rather, a quantum entanglement if applied in the galaxy far far away)

  24. I'm a software developer and wonder how the heck can you make software for this thing, no programming language yet I guess any will do (Superposition code)

  25. Hello there. Ion trap quantum computers are classified as universal quantum computers. You can implement the set of universal gates {C-Phase, C-Not, T, H} on the ion trap system and make up circuits that are equivalent to circuits set up on a superconducting system.

  26. What is the point of having a quantum computer when it operates on chance when we have classical computing which operates on Boolean logic…not chance? How could a person program for a quantum computer when the machine understands one line of code differently each time?

  27. The way I see it is that quantum computers can help you when you’re not sure exactly what you’re looking for and you want a clear path. But they're not fundamentally better than classical computers if you already know what you’re looking for.

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