Joe Rogan - "What Is Quantum Computing?" - Sean Carroll Explains

Well, here's a question that's not totally related, but you might be a good person for this What is quantum computing? Now I keep hearing about this. That's one of the big breakthroughs in in Computers is going to be quantum computing, right? I'm almost the right guy. I'm not completely the right guy I actually did teach a course at Caltech that involved quantum computing. So I'm above average But yeah so So quantum mechanics, this is the book that I'm writing right now It's gonna be out a year from now called something deeply hidden it'll be about quantum mechanics and the goal of the book will be to make quantum mechanics understandable to everybody and convince them that quantum mechanics really does imply the existence of multiple worlds where things look very much the same except for tiny differences and One way of thinking about what quantum mechanics says is in classical mechanics, which is what came before quantum mechanics Let's imagine you have a bit right that is something is either 0 or 1 Right one piece of information in quantum mechanics. You have a quantum bit a qubit as they call it very clever So the difference is that instead of it being a 0 or a 1 like it would be classically quantum mechanically It is in some superposition of 0 and 1 and some combination of a little bit 0 a little bit 1 And it's not that you don't know which one it is. It's that it really is both It might be 90% 0 and 10% 1 or something like that So take that fact number one. Okay Fact number two is that quantum mechanics has a thing called entanglement Which means that if you have two bits Classically, so you have 0 0 0 1 1 0 1 1 right four different possibilities So quantum mechanics says it's not that this one bit is in a combination of 0 and 1 and this other bit is also in a combination of 0 and 1 it's that the 2-bit system is in a combination of 0 0 0 1 1 0 1 1 right so it might be that it's 50% 0 0 and 50% 1 1 So you don't know what either bit is but you know, they're the same right? So that's entanglement so you take these two ideas that the you have a combination of zeros and ones rather than just one or the other and The the different bits can be entangled with each other and then you just say well What is a computer computer is something that takes bits in does manipulations and spits out the answer, right? You solve problems you that's what's literally going on in your computer is a bunch of zeros and ones being pushed around So a quantum computer is pushing around a bunch of qubits, right bunch of spinning particles or something like that the spin of a particle that can either be spinning clockwise or counterclockwise is a qubit and So these particles can interact with each other They can become entangled and you invent a quantum algorithm, right? Like there's algorithms for you know finding the area of a surface or something like that Factoring large numbers, you know solving the shortest distance between two different points You can do this using the rules of quantum mechanics instead of the rules of classical mechanics and the belief Which is not yet a hundred percent established But we think is true is that there are some problems that are really really hard to solve for a classical computer Which means that you can easily make the problem long enough that it would take the lifetime of the universe to solve it on a classical computer Which quantum computers can solve quite quickly and efficiently and so it's we're not we haven't proven that It's not a mathematically wise. Why would they think that quantum computers would be able to solve it quicker? There's more information in the quantum computer. Like if you have two bits zero zero zero one, etc There's only four things it can be right if you have a quantum computer is an infinite number of things It can be because it's any combination of those four things right ten percent this twenty percent that so there's a continuum of possibilities It's it's analog rather than digital in some sense. And so what you what you can do You know the quantum computer can just sort of Take advantage of that extra power To look I mean because of this entanglement what this is this is I'm gonna get in trouble with my quantum computing friends It's not quite fair but roughly speaking rather than manipulating bit by bit Because of the entanglement between the bits the quantum computer can move all the bits a little bit at once So let's say that you're you're searching for something in a list right a very elementary Computer science program is I'm giving you a list find an element that is equal to a certain number, right? It sounds easy. But if that list is 10 trillion things long, that's hard, right? So what the quantum computer can do is they take every element in the list Nudge it a little bit Towards zero if it's the wrong answer and towards one if it's the right answer and you don't know where it is in the list But you can do that nudging over and over again at the end of the day look for where's the one? It's very easy to find So you can get the answer much quicker. It is believed and so things like cryptography privacy right are dramatically changed by this because if one of the things that we think quantum computers should be able to do faster is Factor large numbers, which is the the difficulty in factoring large numbers is the basis for much modern cryptography But also simulating systems that were just too difficult to simulate, you know Just took too much computer power to do it now Maybe we can do it because nature is truly quantum mechanical at the core It turns out to be very hard because the problem is you have all these bits If you touch one of them if the outside world bumps into one of them, right like a cosmic ray or Adam hits it the whole entanglement is ruined between everything so it's very very delicate and That's what the you know right now They're they're working on systems of let's say dozens of qubits entangled at once you would you would like it to be way more than that because you can store an enormous amount of information in these things and If it works as I think it'll be way better at computing if it works I'm not at all sure that quantum computers will be efficient or cost effective or anything like that in the near term But you know doing computations faster is something a lot of people want to be able to do