Quantum Supremacy: When Will Quantum Computers Be a Thing?


Thanks to Brilliant for supporting this episode
of SciShow. Go to Brilliant.org/SciShow to learn more. [♪ INTRO] In 2019, Google researchers announced that
they had achieved quantum supremacy. That does not mean that they’re ushering
in a new sci-fi future. As far as we know. It sounds very grandiose. Instead, it describes what might be the first useful quantum computer, an entirely new way of performing calculations that’s better
than anything we’ve got right now. But not everyone thinks that Google actually
got there, or that quantum supremacy is even a thing worth worrying about. To understand what this means, we’ve got
to go way back to the basics of how computers work. If you’ve been told one thing about a computer, it’s that, deep down, everything is just
ones and zeros. And, amazingly, this very simple fact is more
or less true. The principle behind your everyday modern
computer dates back to a landmark paper published by British computer scientist Alan Turing
in 1936. He described a theoretical device we now call the Turing machine, capable of solving any
problem with just three simple actions. The machine could read a zero or one from
a bit of memory, like a strip of paper. It could also write a zero or one to that
bit of memory, or it could move to an adjacent bit. Mathematicians have proven that by combining those three actions with a set of rules about
when to use each one, the Turing machine is capable of solving any
mathematical problem. It was theoretical at the time, but now every
modern computer is basically just an extremely complicated,
very small, really wonderful Turing machine. These devices now are starting to be called
classical computers. Quantum computers, on the other hand, wait
for this, have bits called qubits that can represent
a zero, a one, or any combination of the two. To understand what that means, we gotta use
quantum physics’ most famous — or infamous — problem. Yes, the cat one. This thought experiment, first proposed by Austrian physicist Erwin Schrödinger, imagined a cat locked in a box with a poison
device. At a random time, the device would activate
and kill the cat. Until you open the box, you can’t know whether the dirty deed has actually happened, so,
in a sense, the cat is both alive and dead while hidden
from view. We’ve simplified this. Now, Schrödinger’s whole point with this
is that the world we’re familiar with — the classical
world — doesn’t work like this. But the quantum world does. The cat is both alive and dead, but only with quantum particles. Now let’s get back to qubits. When you read the value of a qubit, you only
ever get a zero or a one, just like the cat can only ever be alive or
dead in the end. But which you get is all up to chance. Every qubit has a probability of being a zero and a probability of being a one, a combination called a superposition. But what the chances of each are is based
on how the qubit is set up. What’s more, the values of different qubits can be linked together in a process called
quantum entanglement. That means that if you measure the state of one entangled qubit, you also get information about its buddies. This adds up to, well, math. By entangling qubits in certain combinations, engineers can solve some of the same kinds
of problems that they can with classical computers. It’s the combination of superposition and
entanglement that gives quantum computers their theoretical
power. Basically, they should be able to do the same
things, but way faster. In principle, a quantum computer can perform a calculation very quickly by representing
all possible outcomes at once and then finding the correct one. Which brings us back to quantum supremacy. It’s the idea that this approach can solve
some kinds of problems that classical computers can’t
— in a practical amount of time, that is. But unlike the physics that actually makes
quantum computers work, the idea of supremacy, of being better than
classical computers, is pretty imprecise. Like, what counts as an impractical amount
of time? Also, quantum computers might be better only
for certain specific kinds of problems — so does
that matter? Google’s announcement that they had achieved quantum supremacy has put these questions front and center. They constructed a device consisting of 54
qubits, made of tiny loops of superconducting wire and capable of representing around ten quadrillion
states. With it, they created a quantum random number
generator and generated a million numbers in just 200
seconds. And after running some tests on the world’s most powerful supercomputer, they concluded that the machine would take about 10,000 years to do the same thing. But it didn’t take long for a research group
at IBM to respond, claiming they could program the same supercomputer to do the simulation in two and a half days, while also providing extra accuracy. This is why it would be nice to have a more solid definition of quantum supremacy. 2.5 days is not 10,000 years, but it’s still about 1000x slower than 200 seconds. But we also don’t necessarily need a quantum random number generator. Classical ones work fine. So even if this is quantum supremacy, does
that matter? We at SciShow are not qualified to say, but what’s clear is that quantum computers
are getting better. And that has profound implications for the world we live in. Take, for instance, cryptography. Every time you log into your computer or check
your email, your data is protected by encryption. That encryption only works because classical
computers can’t efficiently solve certain kinds of
math problems. The code protecting your bank account, for
instance, isn’t unbreakable — it would just take
so long that the bad guys don’t bother. But what if something that today takes ten
thousand years suddenly takes two hundred seconds? That’s the kind of change quantum computing
represents. In a way, you can think of these machines totally like classical computers in the 1950s. They fill rooms, require tons of power, and are only useful for certain kinds of problems. But year by year, they’re getting smaller
and more powerful. We can debate how much progress has been made, but progress is being made. If history is any indication, we will get there sooner or later. Whenever quantum computers do become a thing, they’re going to need quantum computer programmers. And you can learn computer science for yourself with the courses on Brilliant.org. Like the in-depth course on data structures, which is all about the fundamental ways computers
store and manipulate data. By the end of the course, you’ll know exactly
how computers store data easily and access it
quickly. Brilliant has dozens of courses like this
one. In addition to computer science, they cover science, engineering, and math. Each one is designed to be hands-on and to keep you engaged the whole way through. Courses are even available offline via their
Android and iOS apps so you can keep learning on the go. The first 200 people to sign up at Brilliant.org/SciShow will save 20% on an annual premium subscription. So if you’ve been telling yourself you want
to learn to code, here’s your chance! And by checking them out, you’re helping
support SciShow, so thanks! [♪ OUTRO]

100 Replies to “Quantum Supremacy: When Will Quantum Computers Be a Thing?

  1. Go to http://Brilliant.org/SciShow to try their data structures course. The first 200 subscribers get 20% off an annual Premium subscription.

  2. Wait. If Turing machines are capable of solving ANY mathematical problem doesn't that make any mathematical problem solvable, therefore contradicting the second incompletude theorem and making P=NP?

  3. …supremacy? Really? You could've read some of the discourse that went around on STEM twitter, specifically by PoC, before using that term.
    Really misstepped with that one.

  4. You really butchered this one. Turning machines were purely theoretical, and they cant solve any mathematical problem, ie ther halting problem. Second, schrodinger's cat was a thought experiment to demonstrate the absurdity of quantum mechanic interpretations.

  5. I felt so smart when I knew the things you were talking about. Guess that 1 semester of quantum informatics didn't go to waste after all.

  6. long time = System.currentTimeMillis();

    for(int i = 0; i < 1000000; i++){

    Math.random();

    }

    long elapsed = System.currentTimeMillis() – time;
    System.out.println("Time taken: " + (elapsed / 1000.0) + " seconds");

    Output:
    Time taken: 0.018 seconds

  7. So can a quantum computer crack classical computers encryptions more easily?
    May be useful for weather and particle simulations as well as procedural generation for CGI and games, I guess

  8. I feel for you, Hank. They pick a few examples and suggest that everything changes. In fact, almost nothing changes. Turing complete devices (e.g. smartphones) can do the same as all other similar devices. Quantum computers will only ever do a microscopic fraction of those computations albeit super fast.

    There is no need for your web developer to worry.

  9. So a Quantum computer will have Windows crash so fast that it's crashed before you finish pressing the power button? 😛

  10. That Q-computer would look awesome on the ceiling in my living room. It doesn't need to be SUPREME to draw my admiration!

  11. What was it Einstein said?
    The better our technology, the stupider the majority of people will be?
    Or something like that?

  12. "solving for" = "looking in the box" The answer will always be skewed to the instant it is presented. The quantum realm can not be compared to our 4D realm.

  13. I do wonder how hard it is to just listen to a german sample on how to pronounce someone's name. I don't think i have ever heard someone butcher a name as bad as here. You are science channel, very least you could give an educated try.

  14. 1:57 "any combination of the two"
    No, it can't have any combination. Only combinations that, when the superposition is represented as the vector z * |0〉 + w * |1〉 where z and w are complex numbers, obeys ||z^2|| + ||w^2|| = 1

    You can't make up a combination where the weights are a kind of number with more dimensions than the complex plane (eg quaternions).

    And you can't have 0 * |0〉 + 0 * |1〉 among other invalid vectors.

  15. It's like the guy that fixed my computer locally has 2 masters degrees in AI, from a community college.
    There are many forms of technological knowledge out there.

  16. Well speaking of quantum computing taking jumps ahead in technology pun intended…

    Scientists Predict Quantum Jumps, Turning Physics on Its Head. Found: Schrödinger’s cat, alive and well. So does this mean FTLC / Faster-than-light communication is now possible? And what does this mean for quantum computing?

    https://futurism.com/predict-quantum-jumps-schrodingers-cat

  17. 1M numbers/200s = 5000/s. My home computer runs at 4 GHz and I'm pretty sure generating one random number takes less than 800,000 instructions. What are they talking about when they say it's faster than even super computers?

  18. Even though your channel is a pop sci oriented one and thus not intended for a deep dive into any of the presented topics, there were some factual errors in this video that are not explained by your general approach – which I'm sure you actually are aware of, Hank. Somewhat odd

  19. …'weee…' are still waiting for proof that you can accelerate the decay of ²³²Th by 'quantum-state-transfer' alone, faster than 14 Gyr 'half-life'…lest your hemidemisemiQwaver (sic) be fretfully slow and reminiscent and imitatory of, the famous Turing Halting Problem…

  20. I think the explanation for how a quantum computer works is way too over simplified and gives a bed representation to what a quantum computer would be used for. "A quantum computer can have a 1 or 0 or it can be both at the same time" while this explanation is technically correct it is so overly simplified that it is incorrect. Trinary computers already exist and a quantum computer is not just adding a new bit to computing. Quantum computers work by collapsing wave functions under used with probability equations in cryptography.

  21. Still such a dumb concept. The cat is what it is. Our perception is the only thing questionable and to assume that our perception is focused on one or the other rather than open to either or neither, neither being that the cat isn't in the box and/or the poison won't work, is patronizing.

  22. In other words, Google succeeded. The definition doesn't matter if their CHIP can do in 200 SECONDS what IBM merely CLAIMED, but DID NOT prove, they could do WITH A SUPERCOMPUTER in 2.5 DAYS. Just let all those ratios sink in. Once you do, there is only one conclusion: Google succeeded.

  23. Trying to achieve both quantum supremacy and real AI as soon as possible. What can possibly go wrong with a real AI based on quantum computing?! It'll realize in 0.01 seconds that humanity should cease to exist and in further 0.02 seconds come up with a thousand different scenarios of how to destroy human civilization, and the next 0.5 seconds will initiate all of them.

  24. quantum computers do not become mainstream until the year 2065
    and come with the added controversy of should cybernetically enhanced humans have access to a quantum neural interface

  25. If you had quantum computers that could brute force encryption you'll just need to use quantum computers to make much more complex encryption. So instead of 10,000 years at current computer speeds make ones that can take millions or billions of years, so that it could still take even quantum computers thousands to brute force.
    The reason you'd need the quantum computers to do that encryption is you'll have to do so much bigger calculations with bigger numbers that just encrypting stuff will take more time.

  26. I totally thought the cryptography bit was a lead-in for a sponsorship ad for a VPN and almost clicked out of the rest of the video. I'm conditioned with sponsors to SKIP IT!

  27. I'm not a quantum expert but the hardware approach Google is using seems to have functional applications with potential speed advantage. It should be more than a random number generator. Costs like money time and energy all play factors. It seems to me this line of development will lead to utility in the not too distant future.

  28. Imagine in 2040 your home computers have a symbiotic duel hardware setup. Having a Bit Processor and Qubit Processor on a hybrid fibre optics motherboard. Plus GPU with the same configuration.

  29. Why doesn't anyone ever talk about the cat. As a sentient being it would know first hand if it were alive or dead…

  30. People who are disappointed by the educational level of this presentation expecting too much from a channel peddling useless subscriptions for uneducated.

  31. Depending on your favourite interpretation, of quantum mechanics, quantum computers can be mind-blowing. In the many-worlds model, we 'ask' our quantum computer a question and it 'splits' the labour, across a nearly infinite array of identical computers in parallel universes. Each tries a different solution to the same question and we then (somehow) filter out the correct answer. Wow!

  32. IBM pointed out another problem with Google's announcement: their quantum computer relied on a classical computer doing computation beforehand in order to work. The total amount of computation time was not measured in seconds but hours.

  33. Here's my theory: physicists touch themselves… A lot! Or not at all… Or both. Yeah, I think I'm going to go with a lot.

  34. Shrowdinger butchering foreign names with proud, since 1899. To be fair only idiots would expect any attention to detail besides explaining quantum physics.

  35. I always thought the man was literally saying that every cat is both alive and dead until you go check on it. Which is pretty unfalsifiable

  36. Sounds like a cool album title from a prog rock or technical death metal band. To back up my point, the death metal band Beyond Creation opened up their song Fundamental Process with the line "quantum hypothesis leading to those mystical superpositions".

  37. I'd be willing to bet a dollar that the NSA already has a working computer capable of breaking standard cryptographic ciphers and have been doing it to spy on nation states for years.

  38. 5:44 "Every time you log int your computer"
    That line is largely incorrect in this context. 99% of the time when you log into your computer you are doing a symmetric crypto operation which has no known efficient quantum solution. It is only the asymmetric operations that are currently threatened by quantum. I know it was not your intent, but the way you presented this is fear mongering.

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