WEBVTT - ScienceStuff Classic: What is a Quantum Computer? 0:00:00.200 --> 0:00:02.400 Hey, please take a second and leave us a review 0:00:02.480 --> 0:00:06.279 on Apple Podcasts, Spotify, or wherever you listen to the podcast. 0:00:06.960 --> 0:00:10.240 Thanks a lot, Hey, Happy New year. In case you 0:00:10.280 --> 0:00:13.320 didn't know, twenty twenty five was the Year of Quantum, 0:00:13.440 --> 0:00:16.400 the year where we celebrated the one hundredth anniversary of 0:00:16.480 --> 0:00:20.520 the development the theory of quantum mechanics. So to end 0:00:20.520 --> 0:00:22.720 the year, we're going to re air our episode that 0:00:22.880 --> 0:00:26.639 answers the question what is a quantum computer. It's a 0:00:26.640 --> 0:00:29.880 good episode because it's a nice introduction to quantum ideas 0:00:30.280 --> 0:00:32.760 and you'll hear what it's like to go inside an 0:00:32.920 --> 0:00:36.640 actual quantum computer lab. We'll be back next week with 0:00:36.680 --> 0:00:40.320 a new episode about the science of imagination, What is 0:00:40.360 --> 0:00:43.040 it and how does it work in your brain? So 0:00:43.159 --> 0:00:45.040 be sure to come back next week for that, But 0:00:45.240 --> 0:00:52.040 until then, please enjoy this field trip into the quantum world. Hey, 0:00:52.080 --> 0:00:55.680 welcome to Sigence Stuff, a production of iHeartRadio. My name 0:00:55.720 --> 0:00:57.520 is hoorheitch Ham and to the end of the program, we 0:00:57.600 --> 0:01:01.280 are talking about a technology that made potentially impact the 0:01:01.360 --> 0:01:05.280 life of every single human on Earth and might change 0:01:05.280 --> 0:01:07.720 how we protect data and come up with passwords. It 0:01:07.800 --> 0:01:10.360 might help us make new and exciting materials, and it 0:01:10.480 --> 0:01:16.400 might render cryptocurrencies like Bitcoin and dotgecoin totally useless. I'm 0:01:16.440 --> 0:01:20.800 talking about quantum computers. What are they, how do they work? 0:01:21.040 --> 0:01:23.000 And most exciting is that we're going to get to 0:01:23.120 --> 0:01:26.040 visit one of them and actually hear it in action. 0:01:26.720 --> 0:01:30.279 So power up your curiosity, log in, and let's answer 0:01:30.319 --> 0:01:38.360 the question how do quantum computers work? Hey? Everyone? Okay, 0:01:38.560 --> 0:01:41.520 So when I started this episode, I was both terrified 0:01:41.760 --> 0:01:46.000 and excited. Terrified because explaining anything with the word quantum 0:01:46.240 --> 0:01:49.120 is really hard, but excited because I had heard that 0:01:49.200 --> 0:01:52.920 a friend of mine was making quantum computers just ten 0:01:52.920 --> 0:01:55.440 minutes from my house and this was a great excuse 0:01:55.520 --> 0:01:57.440 for me to go take a look at them. So 0:01:57.440 --> 0:01:59.960 we're going to go see these quantum computers in person 0:02:00.360 --> 0:02:02.560 at the end of the episode, but before that, I 0:02:02.600 --> 0:02:05.000 wanted to make sure that I understood what they were, 0:02:05.320 --> 0:02:08.440 how they work, and also what they're potentially going to 0:02:08.480 --> 0:02:12.280 be used for. So this episode is split into three parts. 0:02:12.560 --> 0:02:14.840 What is a quantum computer and how does it work? 0:02:15.320 --> 0:02:18.160 What are quantum computers for? And then we're going to 0:02:18.160 --> 0:02:20.680 go see the quantum computers. We're going to talk about 0:02:20.720 --> 0:02:23.280 how they're made and why they're so hard to get 0:02:23.320 --> 0:02:25.560 them to work. Our guide through all of this is 0:02:25.560 --> 0:02:28.040 going to be my friend who's making the quantum computers, 0:02:28.240 --> 0:02:31.760 Professor Oscar Pater. He's a professor of physics and applied 0:02:31.760 --> 0:02:35.119 physics at Caltech and he's the head of quantum hardware 0:02:35.440 --> 0:02:39.840 for Amazon. He does research on nanophotonics, quantum optics, and 0:02:39.919 --> 0:02:51.160 of course, quantum computers. Here's my visit to Oscar Painter's lab. A. Hey, 0:02:51.600 --> 0:02:52.240 os Care, how. 0:02:52.200 --> 0:02:54.200 Are you good to see you after so many years. 0:02:54.280 --> 0:02:56.600 Yeah, it's been a while. Huh yeah, well thanks so 0:02:56.639 --> 0:02:57.520 much for talking with me. 0:02:57.639 --> 0:03:00.440 Yeah, it's been a while. Happy to try to fill 0:03:00.480 --> 0:03:02.079 you in on some of the things we've been doing 0:03:02.120 --> 0:03:03.240 in the areas of quantic computing. 0:03:04.080 --> 0:03:05.720 Okay, so the first thing I wanted to talk to 0:03:05.800 --> 0:03:09.400 him about was just what does the word quantum mean? 0:03:09.720 --> 0:03:11.560 Because I feel like we're going to need that to 0:03:11.720 --> 0:03:14.240 understand what a quantum computer is. 0:03:14.919 --> 0:03:15.160 Now. 0:03:15.240 --> 0:03:18.200 The word quantum is the word we used to describe 0:03:18.280 --> 0:03:21.080 how things behave at the level of atoms and the 0:03:21.240 --> 0:03:24.040 tiny little particles that make up the atoms. So in 0:03:24.080 --> 0:03:27.040 our everyday lives, we're used to things being solid and 0:03:27.320 --> 0:03:29.680 us being able to hold them. Like, for example, if 0:03:29.720 --> 0:03:31.960 you take a piece of wood or a ball. But 0:03:32.000 --> 0:03:33.880 if you take that piece of wood or ball and 0:03:33.919 --> 0:03:35.960 you chop it up, and you keep chopping it up, 0:03:36.080 --> 0:03:38.440 you get down to atoms, and then you'll notice that 0:03:38.480 --> 0:03:41.440 those atoms don't behave in the same way that a 0:03:41.480 --> 0:03:44.360 piece of wood or a ball do. Here's how Oscar 0:03:44.440 --> 0:03:45.839 explains it. 0:03:45.840 --> 0:03:48.800 It turns out that down to the microscopic scale, so 0:03:48.880 --> 0:03:51.560 not our everyday scale of things, the laws of physics 0:03:51.560 --> 0:03:54.760 that dominate in that regime is quantum mechanics, and quantum 0:03:54.760 --> 0:03:58.120 mechanics is our theory that has some strange attributes that 0:03:58.160 --> 0:04:01.800 we don't experience every day. Exact ample, it postulates that 0:04:02.000 --> 0:04:05.680 things can be in superposition, so you can have objects 0:04:05.720 --> 0:04:07.440 being in sort of what we think of as two 0:04:07.440 --> 0:04:10.560 distinct realities at the same time. Imagine having a particle 0:04:10.560 --> 0:04:14.520 in one position and another position simultaneously. That seems very 0:04:14.520 --> 0:04:17.360 odd to us, but in quantum mechanics it's very natural. 0:04:18.240 --> 0:04:20.599 Like, for example, I grabbed this piece of wood in 0:04:20.640 --> 0:04:22.320 front of me, and it's a piece of wood. It's 0:04:22.320 --> 0:04:24.719 not two things at the same time, right, It's in 0:04:24.760 --> 0:04:25.400 one location. 0:04:25.640 --> 0:04:27.800 Right, it's sitting there firmly right in front of you. 0:04:27.920 --> 0:04:29.479 Right, if I had an atom in front of me 0:04:29.600 --> 0:04:32.680 or an electron, it wouldn't exactly. 0:04:32.680 --> 0:04:35.000 You would find that if you repeated the measurement or 0:04:35.000 --> 0:04:38.120 finding its position multiple times, you might find that, Oh, 0:04:38.200 --> 0:04:40.920 I get this weird outcome that sometimes I measure it here, 0:04:40.960 --> 0:04:43.440 sometimes I measure it there. And that's because it's actually 0:04:43.480 --> 0:04:46.480 in many places at once, all right, And that's fundamental 0:04:46.560 --> 0:04:49.120 to the description of quantum mechanics. The way I like 0:04:49.160 --> 0:04:53.080 to think about quantum mechanics is really as waves and amplitudes. 0:04:53.279 --> 0:04:55.640 So think about you're at a pond and you throw 0:04:55.640 --> 0:04:57.400 a rock in a pond, and you see this ripple 0:04:57.440 --> 0:04:59.960 of the rock. Right, That's how I think about, Like 0:05:00.080 --> 0:05:02.800 the rocks are sort of the particles, and these wave 0:05:02.800 --> 0:05:06.520 phenomena are sort of the actual physical quantum mechanical description 0:05:06.680 --> 0:05:07.560 of that particle. 0:05:08.160 --> 0:05:11.400 Like the particle, the thing, the atom, or the electron. 0:05:11.600 --> 0:05:13.640 It's not the rock you throw into the pond, no, 0:05:13.720 --> 0:05:16.200 but it's actually the ripple of the ripple. Yeah, that's right, 0:05:16.200 --> 0:05:16.880 it's this wave. 0:05:17.320 --> 0:05:19.560 So I may have started with something that was very local, 0:05:19.600 --> 0:05:22.159 like that rock, but then it becomes very quickly it 0:05:22.200 --> 0:05:24.720 sort of propagates out and is actually better described as 0:05:24.720 --> 0:05:27.120 this wave on the pond, because. 0:05:26.880 --> 0:05:28.720 Like a ripple and a wave in a pond like that, 0:05:28.880 --> 0:05:30.640 it's kind of in a lot of places at the 0:05:30.640 --> 0:05:31.320 same exactly. 0:05:31.680 --> 0:05:34.760 That's right. And then the interference is important to understand. 0:05:34.839 --> 0:05:36.960 If I throw two rocks in the pond, then I 0:05:37.000 --> 0:05:39.640 see the sort of interference of the ripple patterns coming 0:05:39.680 --> 0:05:41.839 from each rock that flashed in the pond. 0:05:41.640 --> 0:05:44.800 Right, Like each ripple starts at simple, but then they 0:05:44.839 --> 0:05:48.200 start to mix together and form this complex pattern on 0:05:48.240 --> 0:05:49.880 the surface of the pod. 0:05:50.240 --> 0:05:53.000 Exactly, like how do they evolve in time? 0:05:54.040 --> 0:05:56.840 Okay, so when you get down to the level of atoms, 0:05:57.160 --> 0:06:01.080 things behave really strangely. Scientists think of things at that 0:06:01.160 --> 0:06:05.000 level not as little tiny balls, but as waves or 0:06:05.200 --> 0:06:08.320 ripples of energy, like the ripples in a pond. Now 0:06:08.320 --> 0:06:10.400 you may think, wait a minute, if things are kind 0:06:10.400 --> 0:06:13.760 of wavy and strange at the level of atoms, why 0:06:13.800 --> 0:06:15.800 isn't it that way when you get to big stuff 0:06:15.839 --> 0:06:18.200 like a piece of wood or a ball. And the 0:06:18.279 --> 0:06:21.320 answer is that they are that way. There's just a 0:06:21.440 --> 0:06:24.200 lot of atoms in a piece of wood, and from 0:06:24.240 --> 0:06:27.240 a distance, it gives you the impression that it's solid. 0:06:28.160 --> 0:06:31.080 It's sort of like how some clouds from Afar they 0:06:31.200 --> 0:06:33.599 might look solid, once you get up close to them, 0:06:33.640 --> 0:06:36.440 they're actually kind of fuzzy and wispy, and all the 0:06:36.480 --> 0:06:40.120 water droplets are moving around. So that's quantum. Now, a 0:06:40.240 --> 0:06:43.919 quantum computer is what happens when you make a regular computer, 0:06:44.360 --> 0:06:47.840 but you make the circuits out of individual atoms or 0:06:47.880 --> 0:06:49.599 particles like electrons. 0:06:51.040 --> 0:06:53.839 Classical computers are formed from things that are very very 0:06:53.839 --> 0:06:55.080 classical in nature. 0:06:54.839 --> 0:06:57.040 And they operate kind of on hard switches. 0:06:57.240 --> 0:06:59.679 Yeah, like, yeah, that's right. The transistors on your phone 0:07:00.000 --> 0:07:02.360 what we call these types of elements. The transistors are 0:07:02.520 --> 0:07:06.039 used to store information or perform calculations, and the transistors 0:07:06.080 --> 0:07:08.560 are really set by a bunch of electrons in part 0:07:08.600 --> 0:07:10.720 of the circuit. And usually you're talking about quite a 0:07:10.800 --> 0:07:12.560 few electrons. 0:07:12.120 --> 0:07:15.920 Because regular transistors are huge. They're bigger than an atom. 0:07:16.040 --> 0:07:18.640 Yes, exactly, that's physically what's going on in your phone. 0:07:18.720 --> 0:07:20.840 And what I'm telling you is that the way to 0:07:20.840 --> 0:07:23.160 think about it is in the quantum case, I just 0:07:23.200 --> 0:07:24.400 have one electron. 0:07:24.280 --> 0:07:27.160 Like, the circuits are made out of individual electrons. 0:07:27.440 --> 0:07:29.680 Yeah, atoms is exactly what you're doing or a quantum 0:07:29.720 --> 0:07:32.040 particle doesn't have to be electrons, can be other particles. 0:07:32.120 --> 0:07:34.600 That was the sort of very early idea from people 0:07:34.640 --> 0:07:37.120 like FIM and others back in the nineteen eighties is 0:07:37.160 --> 0:07:40.320 if you're going to do this, and you better make 0:07:40.400 --> 0:07:42.640 them out of quantum mechanical objects to begin with. 0:07:43.480 --> 0:07:46.280 Okay, So if you make a computer where the circuits 0:07:46.360 --> 0:07:50.800 are made of individual quantum objects like atoms or electrons, 0:07:51.000 --> 0:07:53.680 then you get a quantum computer. And what that does 0:07:53.920 --> 0:07:58.240 is that it makes their calculations also quantum mechanical. And 0:07:58.320 --> 0:08:00.920 this is where the concept of a bit comes in. 0:08:01.240 --> 0:08:04.000 It's like a regular bit in your computer, and a 0:08:04.040 --> 0:08:06.600 bit is like a one or zero, but a cubit 0:08:06.680 --> 0:08:09.440 is a quantum mechanical one or zero. 0:08:11.040 --> 0:08:14.000 Classic computers are formed from digital bits and they go 0:08:14.120 --> 0:08:18.240 between one and zero. A quantum computer doesn't have these 0:08:18.640 --> 0:08:22.200 hard zero one states. It has every possibility in between. 0:08:22.440 --> 0:08:25.120 So imagine if we have these two states zero in one. 0:08:25.760 --> 0:08:27.640 I told you that a quantum system can be in 0:08:27.680 --> 0:08:30.160 two different states at once, right, So it can be 0:08:30.200 --> 0:08:32.520 in zero and one at the same time, and I 0:08:32.640 --> 0:08:34.880 can have a different weight of zero or one at 0:08:34.880 --> 0:08:36.959 the same time. It could be ten percent zero ninety 0:08:36.960 --> 0:08:37.480 percent one. 0:08:38.160 --> 0:08:39.439 It's like a shade of gray. 0:08:39.679 --> 0:08:42.880 Yeah, And so you have all those possibilities in between. 0:08:42.960 --> 0:08:45.760 It can be zero or one or anything in between. 0:08:46.120 --> 0:08:49.240 It can be black, white, dark, gray, light gray exactly. 0:08:49.320 --> 0:08:51.080 So it has all those shades in between. You can 0:08:51.080 --> 0:08:53.680 take zero with some fraction and add it to one 0:08:53.880 --> 0:08:56.640 with any other fraction. You can have any combination of that. 0:08:57.520 --> 0:09:00.960 So an a regular computer, if you multiply two bits together, 0:09:01.160 --> 0:09:05.000 it's like you're multiplying two fixed numbers together, like three 0:09:05.040 --> 0:09:08.240 times four. But in a quantum computer, when you multiply 0:09:08.360 --> 0:09:11.840 two cubits together, it's like you're multiplying two things that 0:09:11.960 --> 0:09:14.920 can be lots of numbers at the same time. So, 0:09:14.960 --> 0:09:18.400 for example, it's like you're multiplying every number from zero 0:09:18.440 --> 0:09:22.080 to one hundred times every number from zero to a thousand, 0:09:22.440 --> 0:09:26.320 all at the same time in one operation. That's what 0:09:26.400 --> 0:09:29.680 makes quantum computers unique. They take this weirdness of the 0:09:29.800 --> 0:09:32.880 quantum world and it lets you do math with it. Now, 0:09:32.920 --> 0:09:36.120 actually it's not doing all of those multiplications or calculations 0:09:36.160 --> 0:09:39.080 at the same time. It's more like how Oscar described 0:09:39.120 --> 0:09:41.760 it earlier. If you drop two rocks in a pond, 0:09:42.080 --> 0:09:45.160 you see the two ripples spread out and mix together 0:09:45.320 --> 0:09:48.800 to form a complex ripple pattern. That's more of the 0:09:48.840 --> 0:09:51.600 picture of what a quantum computer does. It doesn't do 0:09:51.720 --> 0:09:55.720 calculations with hard numbers. It does calculations with the ripples 0:09:55.760 --> 0:10:00.320 and patterns of quantum numbers. Of course, my next question 0:10:00.360 --> 0:10:03.320 for Oscar was what is that good for? Why would 0:10:03.360 --> 0:10:06.720 you want to do math? This way? When we come back, 0:10:06.880 --> 0:10:09.640 I'm going to ask Oscar what quantum computers are for, 0:10:10.360 --> 0:10:12.280 and then at the end we're going to go check 0:10:12.320 --> 0:10:16.640 out the ones he's built. You're listening to science stuff. 0:10:24.000 --> 0:10:27.320 Welcome back. Okay, to recap, we learned that a quantum 0:10:27.360 --> 0:10:30.800 computer is a regular computer whose circuits are made with 0:10:30.960 --> 0:10:35.320 individual atoms or small particles like electrons, and by doing 0:10:35.320 --> 0:10:38.839 that you can do quantum calculations. That is, you can 0:10:38.880 --> 0:10:41.840 do math, but with numbers that are actually lots of 0:10:41.840 --> 0:10:44.880 different numbers at the same time. So now the question 0:10:44.960 --> 0:10:46.680 is why would you want to do that? What are 0:10:46.760 --> 0:10:50.720 quantum computers? Four? Here's more of my conversation with quantum 0:10:50.760 --> 0:10:54.880 physicists Oscar Painter. Let's say it's a few years into 0:10:54.920 --> 0:10:58.320 the future and we have quantum computers, yes, in our phones, 0:10:58.640 --> 0:11:01.120 like I have one in my pocket, what can I 0:11:01.120 --> 0:11:02.680 do with it? And how is my life different? 0:11:04.040 --> 0:11:08.199 I think that's a very unlikely scenario. Okay, I think 0:11:08.280 --> 0:11:11.160 that's the wrong way to think about how quantic computers 0:11:11.240 --> 0:11:14.960 might change our lives, at least as far as I 0:11:14.960 --> 0:11:18.200 can project into the future. I think the best way 0:11:18.200 --> 0:11:21.079 to think about a quantic computer as we envision it 0:11:21.160 --> 0:11:24.800 right now is that it will be more like a supercomputer. 0:11:25.120 --> 0:11:28.040 So a supercomputer is just a very large computer that 0:11:28.160 --> 0:11:32.480 can perform calculations beyond what our desktop, our personal computers 0:11:32.480 --> 0:11:35.559 can do. And these are usually very large, almost building 0:11:35.640 --> 0:11:39.520 scale computers and computer clusters that have many, many different 0:11:39.520 --> 0:11:41.960 processing units that are all integrated together, and through that 0:11:42.120 --> 0:11:45.600 scale you can perform a huge number of computations per 0:11:45.640 --> 0:11:48.199 second and therefore compute some of the hardest problems that 0:11:48.240 --> 0:11:50.160 are out there. A lot of them are used for 0:11:50.400 --> 0:11:54.920 chemistry problems. They're used to study particle physics, so fundamental physics, 0:11:55.000 --> 0:11:58.080 trying to understand models of quantum particles that are beyond 0:11:58.360 --> 0:12:02.200 the current standard model. There used to compute the properties 0:12:02.280 --> 0:12:04.520 of materials, climate modeling, and things like that. 0:12:04.800 --> 0:12:07.360 So usually science and tech, yeahs, and. 0:12:07.280 --> 0:12:10.040 There's always this competition between different nations who has the 0:12:10.160 --> 0:12:12.319 fastest or the biggest supercomputer. 0:12:12.880 --> 0:12:16.400 I see, So you envision quantum computers will be sort 0:12:16.400 --> 0:12:18.520 of like a specialized version of computer. 0:12:18.640 --> 0:12:21.239 It's going to be some very special type of supercomputer 0:12:21.400 --> 0:12:24.520 that can solve specific problems that quantic computers will be 0:12:24.600 --> 0:12:27.760 very effective at that we can't do today on classic computers, 0:12:27.800 --> 0:12:29.840 no matter how much we scale them up. And the 0:12:29.920 --> 0:12:33.520 key is, it's not just a faster supercomputer. It performs 0:12:33.520 --> 0:12:36.800 calculations in a fundamentally different way, and therefore it can 0:12:36.840 --> 0:12:39.880 tackle problems that are possibly outside of the reach of 0:12:39.880 --> 0:12:43.280 these conventional classical supercomputers. What do you mean, out of 0:12:43.320 --> 0:12:46.040 the reach meaning that no matter how fast they get 0:12:46.080 --> 0:12:48.040 or how big they get, they'll never be able to 0:12:48.040 --> 0:12:48.600 compute some. 0:12:48.559 --> 0:12:52.160 Of these problems, never or take an infinite Yeah, exactly. 0:12:52.280 --> 0:12:55.160 It's just the scaling is so bad for these problems. 0:12:55.600 --> 0:12:58.679 You would take way too long and require way too 0:12:58.760 --> 0:13:01.680 large on machine. So no matter how hard we work 0:13:01.720 --> 0:13:05.680 on our current computing technology, it has limits, and it's 0:13:05.720 --> 0:13:08.840 known and you can prove it for certain problems. And 0:13:09.120 --> 0:13:12.720 quantic computers when they looked at theoretically these same problems, 0:13:13.240 --> 0:13:17.160 they realize that the same restrictions or limitations for quantum 0:13:17.160 --> 0:13:21.520 computers are not there. There's examples where we believe and 0:13:21.720 --> 0:13:26.520 strongly believe that certain mathematical problems that are important are 0:13:26.840 --> 0:13:29.640 really really hard to perform and can't be solved using 0:13:29.880 --> 0:13:33.480 classical means, no matter how much we improve the technology. 0:13:33.160 --> 0:13:35.160 No matter if I have a building full of supercomputers, 0:13:35.240 --> 0:13:37.400 yeah exactly, you'll never be able to, say, just fill 0:13:37.440 --> 0:13:37.960 the world with them. 0:13:38.000 --> 0:13:40.319 You still won't be able to do it. Yet a 0:13:40.400 --> 0:13:42.640 quantic computer can solve it pretty efficiently. 0:13:43.640 --> 0:13:45.840 Well, step me through some of these problems. 0:13:45.840 --> 0:13:48.760 Like so the example that everyone points to, and it 0:13:48.800 --> 0:13:53.839 is pretty amazing that people found this, But there's this 0:13:54.000 --> 0:13:56.760 mathematical problem and it just happens to be very applicable 0:13:56.800 --> 0:13:59.280 to our safety or security of our data. So it 0:13:59.320 --> 0:14:02.080 turns out that most of the security of all of 0:14:02.080 --> 0:14:05.080 the data you hold, all the data that banks or 0:14:05.160 --> 0:14:08.240 various institutions around the world want to be safe and protected, 0:14:08.280 --> 0:14:11.480 they typically encrypt it. And those encryption techniques that have 0:14:11.559 --> 0:14:15.480 been used were what are called RSA encryption, where you 0:14:15.520 --> 0:14:18.199 want to take a large number and understand what its 0:14:18.200 --> 0:14:19.040 prime factors are. 0:14:20.000 --> 0:14:23.080 Okay, so the first big thing that quantum computers can 0:14:23.120 --> 0:14:25.880 be useful. The one that got people really excited about 0:14:25.920 --> 0:14:30.520 them in the nineties is in breaking password encryption. So 0:14:30.680 --> 0:14:33.560 whenever you enter your password on a website or when 0:14:33.560 --> 0:14:37.560 you download your bank statement, that information is encrypted or 0:14:37.600 --> 0:14:41.360 scrambled so that if anyone happens to catch that information, 0:14:41.720 --> 0:14:44.960 they can't tell what it says. And the whole scheme 0:14:45.280 --> 0:14:47.440 is based on the idea that if I gave you 0:14:47.480 --> 0:14:50.760 a really large number, it's really hard to find what 0:14:50.840 --> 0:14:54.840 its prime factors are. Here's how Oscar explains it, but 0:14:54.960 --> 0:14:56.920 just to give you a quick heads up, a prime 0:14:57.000 --> 0:14:59.920 number is a number that can't be divided except by 0:15:00.080 --> 0:15:04.160 itself or by one. So, for example, thirteen is a 0:15:04.200 --> 0:15:07.680 prime number because you can't fight thirteen by anything except 0:15:07.880 --> 0:15:12.560 thirteen and one. And the same goes for seventeen, nineteen, 0:15:12.760 --> 0:15:16.800 twenty three and so on. Anyways, here's Oscar explaining it. 0:15:17.600 --> 0:15:19.360 So I give you a number, and I say, tell 0:15:19.360 --> 0:15:21.760 me what the prime factors are, and you have to 0:15:21.800 --> 0:15:24.760 break it down to its prime factors. So you know, 0:15:24.800 --> 0:15:26.560 a simple one is, you know, like two, it's just 0:15:26.640 --> 0:15:28.120 one times two, one and two those are the two 0:15:28.160 --> 0:15:30.440 prime factors, right, But it gets harder as these numbers 0:15:30.440 --> 0:15:30.960 get bigger. 0:15:31.160 --> 0:15:34.720 If I tell you one million, three hundred forty three. 0:15:34.200 --> 0:15:40.480 Yeah, thirteen, very hard to actually answer what those what 0:15:40.520 --> 0:15:42.320 the prime factors are. But if I give you the 0:15:42.320 --> 0:15:44.640 prime factors, you can multiply them together and very quickly 0:15:44.680 --> 0:15:46.600 get the answer to what that larger number is. 0:15:46.680 --> 0:15:46.840 Right. 0:15:47.640 --> 0:15:49.440 And so if you know the prime factors, I can 0:15:49.480 --> 0:15:51.640 give you what they multiply to. But if you give 0:15:51.680 --> 0:15:54.320 me the number that they multiply to without then I 0:15:54.360 --> 0:15:56.800 have a very hard time finding out what the prime factors. 0:15:56.520 --> 0:15:58.400 Are because you'd have to get you kind of have 0:15:58.440 --> 0:15:58.880 to guess. 0:15:59.160 --> 0:16:02.680 Well, you know, there's mathematical techniques to try to find these, 0:16:02.680 --> 0:16:06.360 but they're very inefficient. And so it turns out that 0:16:06.880 --> 0:16:09.800 most of the security of the way we encrypt information 0:16:10.600 --> 0:16:13.280 is based upon that asymmetry and how hard the problem is. 0:16:13.800 --> 0:16:16.040 So now, let's say somebody has a quantum computer. 0:16:15.960 --> 0:16:20.080 Right, then they can find those prime factors and they 0:16:20.080 --> 0:16:21.680 can now decrypt all that information. 0:16:22.400 --> 0:16:25.000 They can just grab it from the air, yeah and 0:16:25.040 --> 0:16:25.680 be like, oh, I. 0:16:25.640 --> 0:16:28.640 Know, yeah, I can find the prime factors and then 0:16:28.640 --> 0:16:31.760 I can use that to decrypt the information. 0:16:32.160 --> 0:16:34.000 That would be easy for a quantum computer you just 0:16:34.040 --> 0:16:36.000 press a button and will tell you, Oh, this is 0:16:36.040 --> 0:16:38.560 an oscar or his secret decoder. 0:16:38.760 --> 0:16:43.920 Yeah exactly, so that would you know. That obviously concerned 0:16:44.160 --> 0:16:47.160 a lot of people when that algorithm was developed. 0:16:48.680 --> 0:16:51.320 Okay, this gets a little bit heavy into encryption and 0:16:51.480 --> 0:16:54.480 quantum algorithms, but the main point is that most of 0:16:54.560 --> 0:16:58.400 the security of our passwords and our sensitive information, and 0:16:58.440 --> 0:17:01.960 also the encryption of things like bitcoin and all those cryptocurrencies, 0:17:02.160 --> 0:17:06.000 they all depend on this one math problem which is 0:17:06.119 --> 0:17:10.159 really hard for regular computers, even supercomputers to solve. And 0:17:10.240 --> 0:17:13.320 that is a problem of finding the two prime numbers 0:17:13.600 --> 0:17:17.200 that multiply to get a really large number. But then 0:17:17.200 --> 0:17:20.200 in nineteen ninety five, a computer scientist named Peter Shore 0:17:20.320 --> 0:17:24.400 publish the paper titled Polynomial time Algorithms for prime factorization 0:17:24.480 --> 0:17:27.879 of discrete logarithms on a quantum computer, which essentially showed 0:17:27.880 --> 0:17:30.359 that if you have a quantum computer, you can solve 0:17:30.359 --> 0:17:33.080 this problem in a short amount of time. And this 0:17:33.160 --> 0:17:35.639 is probably the main reason that people have been rushing 0:17:35.680 --> 0:17:39.400 to make quantum computers since then, because imagine if everyone 0:17:39.440 --> 0:17:43.560 in the world, people, companies, countries are all protecting their 0:17:43.600 --> 0:17:46.639 secrets using the same trick but you had a special 0:17:46.680 --> 0:17:50.120 quantum computer that could break that trick, you could rule 0:17:50.160 --> 0:17:53.719 the world. Now, the details of how Peter Shore's algorithm 0:17:53.760 --> 0:17:56.280 works are a little complicated to explain here, but the 0:17:56.400 --> 0:17:59.000 essence of it is that you're using the ripples on 0:17:59.119 --> 0:18:02.480 au pawn nature of quantum numbers on a quantum computer 0:18:02.720 --> 0:18:06.760 to basically try out every possible combination for how to 0:18:06.760 --> 0:18:10.000 break your secret encryption, and you use some clever math 0:18:10.119 --> 0:18:13.800 tricks so that these ripples combine and mix together until 0:18:13.840 --> 0:18:17.040 the right answer pops out. So that is the main 0:18:17.080 --> 0:18:20.480 reason that people are excited about quantum computers. But there 0:18:20.520 --> 0:18:24.959 are other reasons and other possible applications, So here's Oscar 0:18:25.080 --> 0:18:26.919 telling me about them. 0:18:27.680 --> 0:18:30.760 Another example is maybe more natural to think about, and 0:18:30.760 --> 0:18:32.800 this is where quantum computers were first proposed. It to 0:18:32.840 --> 0:18:36.240 be interesting or useful, and that is the simulation of 0:18:36.680 --> 0:18:41.199 nature itself. Nature as we know it is not classical. 0:18:41.320 --> 0:18:44.240 If you peel the layers of the onion enough and 0:18:44.280 --> 0:18:46.560 you get down to the core, right to the atomic scale, 0:18:46.560 --> 0:18:49.200 it turns out that the laws of physics that dominate 0:18:49.359 --> 0:18:53.240 is quantum mechanics. Okay, like the actual mathematics of that 0:18:53.600 --> 0:18:56.080 When you describe it. When you have many particles, it 0:18:56.560 --> 0:18:59.879 quickly becomes something that you can't simulate with a classical computer. 0:19:00.200 --> 0:19:03.080 So all those interference of all the particles and keeping 0:19:03.119 --> 0:19:05.040 track of all of that. A classical computer, if you 0:19:05.040 --> 0:19:07.399 try to simulate that, you quickly run out of steam 0:19:08.400 --> 0:19:12.040 and it becomes an exponentially hard problem. And so you know, 0:19:12.040 --> 0:19:14.040 a classical computer is just ill suited to doing that. 0:19:14.480 --> 0:19:16.560 But a quantum computer that's made out of the say 0:19:16.640 --> 0:19:19.240 those sort of particles that can do with that interference naturally, 0:19:19.480 --> 0:19:21.720 you know, has a natural advantage in terms of using 0:19:21.720 --> 0:19:24.800 it to simulate the natural world at its quantum mechanical core. 0:19:25.280 --> 0:19:26.240 Why would I want to do that? 0:19:26.600 --> 0:19:28.879 Yeah, so that's the questions like, okay, so that's great, 0:19:29.040 --> 0:19:30.439 But why would I want to do that other than 0:19:30.440 --> 0:19:33.959 maybe I want to understand physics better. Well, this idea 0:19:34.000 --> 0:19:36.440 that I want to understand how material behaves is a 0:19:36.520 --> 0:19:38.840 very good example. If I'm building an electrical circuit, or 0:19:38.880 --> 0:19:42.640 I'm building a new battery, or I'm building a different 0:19:42.760 --> 0:19:45.720 energy process inside of a material or energy storage device, 0:19:46.040 --> 0:19:47.800 A lot of times that depends on what the electrons 0:19:47.800 --> 0:19:50.960 are doing. If I want to understand is there something 0:19:51.080 --> 0:19:53.639 unique when I describe them quantum mechanically. Maybe there's special 0:19:53.640 --> 0:19:56.680 properties I'm just totally blind to. So if I wanted 0:19:56.680 --> 0:19:59.840 to make a better superconnecting material, something that can carry 0:19:59.840 --> 0:20:03.360 a electricity with no resistance, right, maybe we can have 0:20:03.720 --> 0:20:07.120 magnetically livitated trains. Maybe you can have you know, really 0:20:07.119 --> 0:20:10.240 efficient electrical circuits that don't dissipate any energy. All of 0:20:10.240 --> 0:20:12.000 these things. Then I would have to use a quantic 0:20:12.040 --> 0:20:13.440 computer to model that behavior. 0:20:14.000 --> 0:20:16.680