1 00:00:15,356 --> 00:00:15,796 Speaker 1: Pushkin. 2 00:00:21,196 --> 00:00:24,676 Speaker 2: In a world where you can put billions of transistors 3 00:00:24,716 --> 00:00:28,756 Speaker 2: on a single chip, and where anybody can access trillions 4 00:00:28,796 --> 00:00:32,036 Speaker 2: of transistors in the cloud, it feels like we can 5 00:00:32,156 --> 00:00:36,236 Speaker 2: use computers for for, you know, anything that can be computed. 6 00:00:37,076 --> 00:00:41,036 Speaker 2: Kind of amazingly, this is not true. There are lots 7 00:00:41,116 --> 00:00:44,756 Speaker 2: of things that could theoretically be computed, but that in 8 00:00:44,836 --> 00:00:48,396 Speaker 2: fact are just too complex, too hard to compute for 9 00:00:48,636 --> 00:00:52,236 Speaker 2: even a cloud full of computers. Things like predicting how 10 00:00:52,356 --> 00:00:56,316 Speaker 2: prospective drugs will work in the body, or modeling really 11 00:00:56,356 --> 00:01:00,636 Speaker 2: complex financial scenarios, even figuring out the factors of very 12 00:01:00,716 --> 00:01:04,396 Speaker 2: large numbers. There are all kinds of computations that people 13 00:01:04,836 --> 00:01:08,956 Speaker 2: just don't do because computers are not nearly powerful enough 14 00:01:08,996 --> 00:01:15,236 Speaker 2: to do them. But but there is an entirely new 15 00:01:15,356 --> 00:01:18,836 Speaker 2: kind of computer people are trying to build. It's called 16 00:01:18,876 --> 00:01:22,636 Speaker 2: a quantum computer. You've probably heard of this. Quantum computers. 17 00:01:22,716 --> 00:01:25,356 Speaker 2: If they work like people hope, they will, will be 18 00:01:25,476 --> 00:01:29,396 Speaker 2: profoundly more powerful than any cloud full of computers that 19 00:01:29,436 --> 00:01:32,756 Speaker 2: has ever existed. They could allow for new breakthroughs in 20 00:01:32,956 --> 00:01:37,076 Speaker 2: everything from drug design to energy storage. Also, a big 21 00:01:37,196 --> 00:01:41,356 Speaker 2: quantum computer could factor very large numbers, which would allow 22 00:01:41,396 --> 00:01:44,196 Speaker 2: it to crack the encryption codes that secure most of 23 00:01:44,236 --> 00:01:52,996 Speaker 2: the data that flows across the Internet. I'm Jacob Goldstein 24 00:01:53,036 --> 00:01:55,316 Speaker 2: and this is What's Your Problem, the show where I 25 00:01:55,436 --> 00:01:58,556 Speaker 2: talk to people who are trying to make technological progress. 26 00:01:58,996 --> 00:02:02,516 Speaker 2: My guest today is Chris Munro. He's the co founder 27 00:02:02,556 --> 00:02:06,596 Speaker 2: and chief scientist at IONQ, one of several companies that 28 00:02:06,716 --> 00:02:09,116 Speaker 2: is trying to figure out how to build a big, power, 29 00:02:09,116 --> 00:02:13,636 Speaker 2: powerful quantum computer. Chris is also a physics professor at Duke, 30 00:02:14,116 --> 00:02:16,756 Speaker 2: which was good news for me because a big part 31 00:02:16,796 --> 00:02:18,796 Speaker 2: of what I wanted to talk to him about was 32 00:02:18,956 --> 00:02:22,476 Speaker 2: quantum physics, which is of course amazing and weird and 33 00:02:22,876 --> 00:02:29,156 Speaker 2: essential for understanding how quantum computers work. We started off 34 00:02:29,196 --> 00:02:33,956 Speaker 2: by discussing the fundamental difference between quantum computers and regular computers. 35 00:02:34,316 --> 00:02:37,556 Speaker 2: It comes down to the bit, the basic building block 36 00:02:37,636 --> 00:02:40,436 Speaker 2: of computing. The essential thing to know about a bit 37 00:02:40,836 --> 00:02:42,716 Speaker 2: is that it can be in one of two states, 38 00:02:43,116 --> 00:02:46,796 Speaker 2: on or off zero or one. At least that's the 39 00:02:46,836 --> 00:02:51,436 Speaker 2: case for traditional computers. Quantum computers use bits called quantum 40 00:02:51,476 --> 00:02:54,916 Speaker 2: bits or cubits, and they're different than traditional bits in 41 00:02:54,956 --> 00:02:57,436 Speaker 2: a really strange, really profound way. 42 00:02:58,436 --> 00:03:03,156 Speaker 3: A quantum bit can be in both zero and one 43 00:03:04,036 --> 00:03:07,276 Speaker 3: at the same time. So this is totally new. We 44 00:03:07,356 --> 00:03:11,876 Speaker 3: never experience, you know, a coffee cup being in two places. 45 00:03:11,916 --> 00:03:12,476 Speaker 3: I'm looking at a. 46 00:03:12,476 --> 00:03:14,996 Speaker 2: Coffee cup here, yes, or more simply a light switch 47 00:03:15,076 --> 00:03:17,276 Speaker 2: that is both on and off. Right, plainly, the light 48 00:03:17,636 --> 00:03:18,516 Speaker 2: is either on or. 49 00:03:18,516 --> 00:03:21,076 Speaker 3: You don't experience those things in everyday life. So here's 50 00:03:21,796 --> 00:03:25,596 Speaker 3: my physics, my two minute description of quantum. Okay, there 51 00:03:25,596 --> 00:03:28,836 Speaker 3: are exactly two rules, no more, no less. There are 52 00:03:28,836 --> 00:03:31,156 Speaker 3: two rules, and they have almost nothing to do with 53 00:03:31,156 --> 00:03:33,196 Speaker 3: each other. Here are the two rules. Okay. The first 54 00:03:33,236 --> 00:03:36,596 Speaker 3: rule is that a quantum system can exist in multiple 55 00:03:36,636 --> 00:03:39,476 Speaker 3: states two. It could be more, but let's just say 56 00:03:39,476 --> 00:03:42,996 Speaker 3: two a cubit it's in both states at the same time. 57 00:03:43,636 --> 00:03:46,436 Speaker 3: And this is not this rule by itself. If you 58 00:03:46,516 --> 00:03:49,676 Speaker 3: think about what's going on, it's not such a big deal. 59 00:03:49,716 --> 00:03:53,636 Speaker 3: And the reason is a quantum system follows a wave 60 00:03:53,716 --> 00:03:56,916 Speaker 3: equation sort of like water waves. That if I throw 61 00:03:56,916 --> 00:04:00,196 Speaker 3: a pebble in the pond, it's going to emanate these 62 00:04:00,276 --> 00:04:03,076 Speaker 3: circular waves that occupy the entire pond. 63 00:04:03,356 --> 00:04:05,316 Speaker 2: So you throw a rock or a ball into the 64 00:04:05,316 --> 00:04:07,556 Speaker 2: pond a minute later wears the waves like the whole 65 00:04:07,556 --> 00:04:08,076 Speaker 2: pond is way. 66 00:04:08,156 --> 00:04:09,996 Speaker 3: Yeah, that's right, that's right, it's not you know, the 67 00:04:10,036 --> 00:04:12,516 Speaker 3: wave is not localized is kind of technically how we 68 00:04:12,596 --> 00:04:17,036 Speaker 3: say something, So it's in many places. Now, that's rule 69 00:04:17,116 --> 00:04:19,156 Speaker 3: number one. So here's rule number two, which is the 70 00:04:19,156 --> 00:04:22,276 Speaker 3: weird one. Rule number two basically says that that wave, 71 00:04:22,516 --> 00:04:27,836 Speaker 3: like that wavelike superposition that all quantum systems can can 72 00:04:27,956 --> 00:04:31,236 Speaker 3: exist in, only works when you're not looking. 73 00:04:32,796 --> 00:04:36,116 Speaker 2: So yeah, that's the part that seems like dumb is 74 00:04:36,156 --> 00:04:39,436 Speaker 2: not quite the right word, but lengthy, implausible, little goofy, 75 00:04:40,076 --> 00:04:43,436 Speaker 2: like surely the world can't give a shit whether I'm 76 00:04:43,476 --> 00:04:44,396 Speaker 2: looking at it or not. 77 00:04:44,876 --> 00:04:46,796 Speaker 3: Yeah, because what I mean, and what happens when you 78 00:04:46,836 --> 00:04:49,396 Speaker 3: do look, and quantum says that when you do look 79 00:04:50,156 --> 00:04:55,516 Speaker 3: the superposition, it pops, It latches onto a definite state, 80 00:04:56,036 --> 00:04:58,836 Speaker 3: so it localizes, and it does it at random. You 81 00:04:58,876 --> 00:05:01,516 Speaker 3: can't predict where it's going to localize. All you can 82 00:05:01,956 --> 00:05:03,916 Speaker 3: say is, well, is supposed to be in these two positions, 83 00:05:03,916 --> 00:05:05,476 Speaker 3: and I looked at it it was in one position. 84 00:05:06,276 --> 00:05:08,436 Speaker 2: More to the point, I mean, are like more to 85 00:05:08,476 --> 00:05:10,796 Speaker 2: the point, as people are first thinking about this, are 86 00:05:10,796 --> 00:05:13,756 Speaker 2: they they're thinking of an electron. So the electron is 87 00:05:13,916 --> 00:05:16,796 Speaker 2: like a wave it kind of exists in all these 88 00:05:16,796 --> 00:05:22,516 Speaker 2: different places around the nucleus. But then they figure out 89 00:05:22,596 --> 00:05:25,316 Speaker 2: if you look at an electron what happens. 90 00:05:25,316 --> 00:05:30,356 Speaker 3: It pops into one state that almost has no space. 91 00:05:30,436 --> 00:05:32,476 Speaker 3: I mean, it pops into a point like particle, like 92 00:05:32,476 --> 00:05:33,556 Speaker 3: a little tiny baseball. 93 00:05:34,556 --> 00:05:37,236 Speaker 2: And if you're not looking at it, is it literally not? There? 94 00:05:37,476 --> 00:05:37,636 Speaker 2: Is that? 95 00:05:38,596 --> 00:05:40,476 Speaker 3: Now you're getting philosophical on me. 96 00:05:40,556 --> 00:05:44,596 Speaker 2: Here, you did it. You're the one telling me these things. 97 00:05:45,516 --> 00:05:47,556 Speaker 3: That's right, Well, it's these two rules. We have to 98 00:05:47,596 --> 00:05:49,316 Speaker 3: add that rule because. 99 00:05:49,476 --> 00:05:51,996 Speaker 2: So so yeah, so state the rules again, just to 100 00:05:52,116 --> 00:05:53,036 Speaker 2: keep us on the rails here. 101 00:05:53,196 --> 00:05:55,956 Speaker 3: Rule number one, any quantum system like a cubit or 102 00:05:55,956 --> 00:05:59,476 Speaker 3: an electron, can be in a superposition of states. It 103 00:05:59,516 --> 00:06:01,156 Speaker 3: can be in this fuzzy existence. 104 00:06:01,876 --> 00:06:03,876 Speaker 2: It can be in two places at once. It can 105 00:06:03,956 --> 00:06:04,876 Speaker 2: be on and off. 106 00:06:05,036 --> 00:06:09,516 Speaker 3: Rule number two is that that first rule only works 107 00:06:09,516 --> 00:06:11,676 Speaker 3: when you don't look, and when you do look, it 108 00:06:11,716 --> 00:06:15,916 Speaker 3: will randomly localize pop out into a singular place. 109 00:06:16,636 --> 00:06:19,436 Speaker 2: It will cease being on and off. It will become 110 00:06:19,556 --> 00:06:23,396 Speaker 2: either on or off. Famously, the cat will stop being 111 00:06:23,396 --> 00:06:27,036 Speaker 2: both dead and alive, and will either be dead or alive. 112 00:06:27,916 --> 00:06:30,796 Speaker 2: And just to be clear, observed, doesn't just mean us 113 00:06:30,836 --> 00:06:33,356 Speaker 2: looking at it, right, that's the kind of caricaturish version. 114 00:06:33,436 --> 00:06:36,236 Speaker 2: But in fact it means like no particle can touch 115 00:06:36,276 --> 00:06:40,116 Speaker 2: it or something like that. Right, So observed doesn't just 116 00:06:40,236 --> 00:06:43,516 Speaker 2: mean seen by a person. It means interacted with by 117 00:06:43,556 --> 00:06:45,756 Speaker 2: any part of it, by anything, even a single molecule 118 00:06:45,756 --> 00:06:49,796 Speaker 2: of air or a photon. One. All of that ruins 119 00:06:49,836 --> 00:06:53,636 Speaker 2: our beautiful superposition and forces the thing to resolve. So 120 00:06:54,036 --> 00:06:56,716 Speaker 2: there's two pieces of jargon that I always come across 121 00:06:56,756 --> 00:07:00,836 Speaker 2: when I'm reading about quantum computers. One, I think you've 122 00:07:00,876 --> 00:07:05,436 Speaker 2: just described one, this idea that quantum things can be 123 00:07:05,596 --> 00:07:09,516 Speaker 2: both one and zero if we're not looking at them, 124 00:07:09,676 --> 00:07:11,476 Speaker 2: is it right, that's called superpositions. 125 00:07:11,516 --> 00:07:14,716 Speaker 3: Yes, that's called That's a I would call it a 126 00:07:14,716 --> 00:07:16,756 Speaker 3: plain old superposition. And you'll see what I. 127 00:07:16,756 --> 00:07:22,876 Speaker 2: Meanilla superposition, no sprints, right, Okay, good, So we've talked 128 00:07:22,876 --> 00:07:26,196 Speaker 2: about superposition. There is this other piece of jargon that 129 00:07:26,196 --> 00:07:29,396 Speaker 2: people always use when they are talking about quantum computing, 130 00:07:29,556 --> 00:07:34,036 Speaker 2: and that is entanglement. So just like we'll get to 131 00:07:34,276 --> 00:07:36,956 Speaker 2: what it means for the computer, but just like, in 132 00:07:36,996 --> 00:07:38,836 Speaker 2: a basic way, what is entanglement. 133 00:07:39,516 --> 00:07:41,996 Speaker 3: What's interesting is that we're bringing Einstein in here. All 134 00:07:42,036 --> 00:07:45,036 Speaker 3: the time. He had a famous paper in nineteen thirty 135 00:07:45,076 --> 00:07:49,756 Speaker 3: five that he thought finally put the end to quantum mechanics. 136 00:07:50,396 --> 00:07:54,476 Speaker 3: He said, and this is ridiculous because these two cubits, 137 00:07:54,596 --> 00:07:57,196 Speaker 3: and I'm gonna, I'm going to use cubits are so simple. 138 00:07:57,236 --> 00:08:00,236 Speaker 3: Here you have two cubits prepared in zero zero and 139 00:08:00,276 --> 00:08:03,196 Speaker 3: one one. Then you separate them. They could be really 140 00:08:03,236 --> 00:08:09,396 Speaker 3: far apart. Nevertheless, when one person measures their cubit, they 141 00:08:09,436 --> 00:08:13,436 Speaker 3: know immediately even before the even before light could traverse 142 00:08:13,436 --> 00:08:16,156 Speaker 3: the distance between them, they know immediately the state of 143 00:08:16,236 --> 00:08:21,836 Speaker 3: the other one. And that violates relativity. Another of Einstein said, right. 144 00:08:21,916 --> 00:08:25,276 Speaker 2: So Einstein has this paper if I as I understand it, 145 00:08:25,316 --> 00:08:28,316 Speaker 2: where he basically says, look, if quantum mechanics is true, 146 00:08:28,916 --> 00:08:33,836 Speaker 2: there will be these particles, whatever very small particles that 147 00:08:33,876 --> 00:08:37,836 Speaker 2: behave in quantum ways, that become connected to each other 148 00:08:37,916 --> 00:08:40,636 Speaker 2: in some strange way. They're not physically connected. You can 149 00:08:40,636 --> 00:08:41,956 Speaker 2: put them as far apart as you want, you can 150 00:08:41,996 --> 00:08:45,076 Speaker 2: put them a million miles away. And if you look 151 00:08:45,116 --> 00:08:48,636 Speaker 2: at one of the particles and it resolves itself into 152 00:08:48,676 --> 00:08:53,156 Speaker 2: some position whatever, call it zero or one instantly, instantly, 153 00:08:53,276 --> 00:08:57,116 Speaker 2: at that same instant, the other particle will resolve itself 154 00:08:57,156 --> 00:09:00,956 Speaker 2: the same way, and surely that can't be true because 155 00:09:00,996 --> 00:09:03,236 Speaker 2: that doesn't make any sense. The universe doesn't work that way, 156 00:09:03,276 --> 00:09:07,036 Speaker 2: and therefore quantum physics is wrong. Question spooky action at 157 00:09:07,076 --> 00:09:08,756 Speaker 2: a distance, he said, mocking list. 158 00:09:08,796 --> 00:09:11,076 Speaker 3: Yes, indeed, the title of the paper was a question 159 00:09:11,196 --> 00:09:13,716 Speaker 3: can quantum mechanics be considered complete? In other words, is 160 00:09:13,716 --> 00:09:15,036 Speaker 3: it right? There's something else there? 161 00:09:15,076 --> 00:09:17,276 Speaker 2: And he's saying, surely, if this could be true, the 162 00:09:17,276 --> 00:09:19,716 Speaker 2: theory must not make any sense because this obviously can't 163 00:09:19,756 --> 00:09:20,116 Speaker 2: be true. 164 00:09:20,196 --> 00:09:22,356 Speaker 3: Yeah, and he was wrong. He was famously wrong. It 165 00:09:22,436 --> 00:09:25,316 Speaker 3: spent tested time and time again that this is exact. 166 00:09:25,596 --> 00:09:28,756 Speaker 3: This is actually how nature works. We have to think 167 00:09:28,796 --> 00:09:29,356 Speaker 3: of it this way. 168 00:09:29,636 --> 00:09:32,876 Speaker 2: And people in China did one recently right where they 169 00:09:33,236 --> 00:09:36,076 Speaker 2: had one particle on the ground and an entangled particle 170 00:09:36,156 --> 00:09:39,116 Speaker 2: on a satellite, and they looked at the particle on 171 00:09:39,156 --> 00:09:41,196 Speaker 2: the ground and it resolved itself in whatever way, and 172 00:09:41,276 --> 00:09:43,036 Speaker 2: at the same moment the particle on this I mean, 173 00:09:43,076 --> 00:09:45,236 Speaker 2: I know that's the party trick version of it, but 174 00:09:45,356 --> 00:09:46,356 Speaker 2: it's a good party trick. 175 00:09:46,476 --> 00:09:49,356 Speaker 3: Yeah. So entanglement is I like to think of it. 176 00:09:49,756 --> 00:09:51,476 Speaker 3: You know, if we move on to quantum computing. I 177 00:09:51,716 --> 00:09:53,396 Speaker 3: like to think of entanglement as sort of like a 178 00:09:53,476 --> 00:09:58,836 Speaker 3: wire without any wires. Yeah, and when you're talking about computing, 179 00:09:58,916 --> 00:10:01,876 Speaker 3: that's in fact what gives quantum computers its power, the 180 00:10:01,916 --> 00:10:04,276 Speaker 3: ability to wire things together without having wires. 181 00:10:05,196 --> 00:10:09,636 Speaker 2: Yeah. So okay, so we've got these two idea, right. 182 00:10:09,716 --> 00:10:11,756 Speaker 2: Superposition a thing can be in two states at once 183 00:10:11,836 --> 00:10:15,316 Speaker 2: until you look at it, and entanglement meaning particles, and 184 00:10:15,356 --> 00:10:17,836 Speaker 2: it's not just two, right, it can be multiple particles 185 00:10:17,876 --> 00:10:20,676 Speaker 2: can be entangled such that when you look at one 186 00:10:20,756 --> 00:10:23,676 Speaker 2: and it resolves into some state, you will immediately know 187 00:10:23,716 --> 00:10:25,916 Speaker 2: what state all the others are resulting into. Right, These 188 00:10:25,956 --> 00:10:31,036 Speaker 2: are the two intellectual tools we've got. Can we build 189 00:10:31,076 --> 00:10:33,716 Speaker 2: a computer in our minds from these two tools? 190 00:10:33,756 --> 00:10:35,916 Speaker 3: Well, the good news is that there's a cool scaling 191 00:10:35,996 --> 00:10:38,916 Speaker 3: law because when we go to three cubits, now there's 192 00:10:39,076 --> 00:10:43,916 Speaker 3: eight states, it's zero one, yes, all three cube, all 193 00:10:43,956 --> 00:10:47,116 Speaker 3: three bit numbers, there's eight of them. With four, there's sixteen, 194 00:10:47,236 --> 00:10:49,636 Speaker 3: thirty two, and so on and so forth. So every 195 00:10:49,636 --> 00:10:53,636 Speaker 3: time you add one cubit, you've just doubled the possibilities. 196 00:10:53,756 --> 00:10:57,116 Speaker 2: Yes, exponentially is an overused word, but this is an 197 00:10:57,156 --> 00:10:58,516 Speaker 2: actual exponential thing. 198 00:10:58,516 --> 00:11:01,516 Speaker 3: And this is the structure of quantum computing that gives 199 00:11:01,516 --> 00:11:04,116 Speaker 3: it its power to calculate things that we could never 200 00:11:04,156 --> 00:11:07,516 Speaker 3: do using classical computer. It's this fundamental exponential gain. 201 00:11:08,036 --> 00:11:10,396 Speaker 2: I get more or less the theory of a quantum computer. 202 00:11:10,516 --> 00:11:13,316 Speaker 2: It's also clear that quantum computers don't exist in a 203 00:11:13,396 --> 00:11:18,516 Speaker 2: useful way yet, right So what do you and everybody 204 00:11:18,596 --> 00:11:20,476 Speaker 2: in the field have to figure out to get from 205 00:11:20,516 --> 00:11:23,916 Speaker 2: where we are now to having amazing quantum. 206 00:11:23,676 --> 00:11:27,356 Speaker 3: Well, in our case using these atoms, it's a simple 207 00:11:27,356 --> 00:11:31,116 Speaker 3: matter of scaling. We routinely work with twenty to thirty 208 00:11:31,196 --> 00:11:33,076 Speaker 3: right now. As soon as we get up to about 209 00:11:33,116 --> 00:11:37,036 Speaker 3: one hundred, we're going to start to challenge will be 210 00:11:37,076 --> 00:11:41,836 Speaker 3: well beyond what challenges supercomputers, and that's where the opportunities 211 00:11:41,876 --> 00:11:44,396 Speaker 3: will happen. And the trick is, with one hundred cubits, 212 00:11:44,436 --> 00:11:46,196 Speaker 3: you need to do a lot of stuff with them. 213 00:11:46,396 --> 00:11:48,396 Speaker 3: You need to do many more operations. They have to 214 00:11:48,436 --> 00:11:51,956 Speaker 3: live longer, they have to be even more isolated as 215 00:11:51,996 --> 00:11:56,636 Speaker 3: you add more. So it's a tricky scaling problem. Our 216 00:11:56,676 --> 00:11:59,156 Speaker 3: technology we sort of we sort of know how to 217 00:11:59,196 --> 00:12:02,516 Speaker 3: do this. Other technologies are still in the lab. I 218 00:12:02,516 --> 00:12:05,476 Speaker 3: think they don't know the underlying physics of materials to 219 00:12:05,516 --> 00:12:08,036 Speaker 3: make them clean enough to do. That doesn't mean we're 220 00:12:08,036 --> 00:12:11,036 Speaker 3: out of the woods. The challenge here is what you said, 221 00:12:11,196 --> 00:12:14,316 Speaker 3: is trying to isolate it the control. But these challenges 222 00:12:14,356 --> 00:12:16,956 Speaker 3: have nothing to do with quantum. It has to do 223 00:12:16,996 --> 00:12:18,636 Speaker 3: with how good of a vacuum, how goods your chip, 224 00:12:18,636 --> 00:12:20,316 Speaker 3: how good are your laser beams. These are all things 225 00:12:20,316 --> 00:12:21,156 Speaker 3: that can be engineered. 226 00:12:21,796 --> 00:12:24,756 Speaker 2: So it's it's very you're like a construction guy, like 227 00:12:24,876 --> 00:12:28,676 Speaker 2: your core problem is just building whatever a box to 228 00:12:28,756 --> 00:12:31,116 Speaker 2: put an atom in so that the atom will be 229 00:12:31,196 --> 00:12:36,516 Speaker 2: left alone to exist in its unobserved quantum stamp. 230 00:12:36,996 --> 00:12:41,876 Speaker 3: Yep, exactly. Quantum systems only exist that way rule number one, 231 00:12:42,316 --> 00:12:47,196 Speaker 3: you know, without looking that meaning that they're nearly perfectly isolated. Yeah, 232 00:12:47,236 --> 00:12:50,556 Speaker 3: so that's the hard part of building a big quantum computer. 233 00:12:52,996 --> 00:12:56,716 Speaker 2: So that's the theory. After the break the practice how 234 00:12:56,756 --> 00:12:58,036 Speaker 2: to build a small. 235 00:12:57,796 --> 00:13:08,876 Speaker 1: Quantum computer form real. Now back to the show. 236 00:13:09,516 --> 00:13:12,836 Speaker 2: A bunch of companies are building quantum computers, big companies 237 00:13:12,916 --> 00:13:15,876 Speaker 2: like IBM and Google and Microsoft, as well as a 238 00:13:15,876 --> 00:13:19,276 Speaker 2: few smaller companies like ion Q. The different companies are 239 00:13:19,276 --> 00:13:23,316 Speaker 2: trying different approaches. Some require super cold temperatures, in your 240 00:13:23,356 --> 00:13:29,916 Speaker 2: absolute zero. Some use photons. Ion Q uses ions charged particles. 241 00:13:30,596 --> 00:13:33,276 Speaker 2: I asked Chris to walk me through how ion Q 242 00:13:33,516 --> 00:13:37,356 Speaker 2: builds a quantum computer and so what so lest I 243 00:13:37,356 --> 00:13:39,796 Speaker 2: mean your company is called ion Q, right, and so 244 00:13:39,916 --> 00:13:43,076 Speaker 2: let's like tell me about tell me about your qubits? 245 00:13:43,476 --> 00:13:45,596 Speaker 2: What what kind of atom? What kind of ion? Like 246 00:13:45,636 --> 00:13:46,556 Speaker 2: what is it that you're using. 247 00:13:47,356 --> 00:13:50,756 Speaker 3: The first few generations were uturbium one seventy one. It's 248 00:13:50,756 --> 00:13:53,596 Speaker 3: a very heavy yes, a heavy atom, the lower right 249 00:13:53,636 --> 00:13:55,836 Speaker 3: part of the periodic table. And it turns out that 250 00:13:55,956 --> 00:13:58,636 Speaker 3: it interacts with the lasers in a very simple way, 251 00:13:58,716 --> 00:14:00,636 Speaker 3: I believe it or not. Okay, so that's what we use. 252 00:14:00,676 --> 00:14:03,036 Speaker 3: It's a metal. So we have a little wire of uturbuum. 253 00:14:03,036 --> 00:14:05,676 Speaker 2: So you have a little piece of metal that's U turbium. 254 00:14:05,876 --> 00:14:07,556 Speaker 2: I would if I were you, I would sell visors 255 00:14:07,556 --> 00:14:08,436 Speaker 2: that said uturbuum. 256 00:14:09,356 --> 00:14:11,916 Speaker 3: That's not sure. Oh yeah, okay, all kinds of swag. 257 00:14:13,236 --> 00:14:16,996 Speaker 2: So okay, so you take this element, this metal U turbium. 258 00:14:17,676 --> 00:14:18,236 Speaker 2: Go it is. 259 00:14:18,556 --> 00:14:21,836 Speaker 3: We have a little vacuum chamber. It's small. They're getting 260 00:14:21,916 --> 00:14:24,476 Speaker 3: those are getting smaller. It's all at room temperature. By 261 00:14:24,476 --> 00:14:27,316 Speaker 3: the way, we don't have to cool things as aggressive o. 262 00:14:27,836 --> 00:14:30,756 Speaker 3: This little wire is inside that vacuum chamber, and there's 263 00:14:30,796 --> 00:14:34,516 Speaker 3: a few black magic things that happen. It's nothing, nothing 264 00:14:34,596 --> 00:14:37,876 Speaker 3: super fancy here. We blast a piece of that metal 265 00:14:37,876 --> 00:14:39,916 Speaker 3: with a laser beam and what happens is we get 266 00:14:39,956 --> 00:14:44,516 Speaker 3: a puff of metal in gas in vapor form. Its sublimates. 267 00:14:44,996 --> 00:14:48,356 Speaker 2: It goes straight from solid to gas without being a liquid. 268 00:14:48,316 --> 00:14:50,596 Speaker 3: In a vacuum chamber. So there's nothing else there, and 269 00:14:50,636 --> 00:14:53,316 Speaker 3: so we get this puff of neutral atoms. Now we 270 00:14:53,356 --> 00:14:57,876 Speaker 3: have these electric fields from chips that again, nothing really 271 00:14:57,876 --> 00:15:01,436 Speaker 3: fancy there. The atoms don't see the electric field because 272 00:15:01,476 --> 00:15:05,436 Speaker 3: the atoms are not charged electrically yet they're neutral. Now, 273 00:15:05,516 --> 00:15:07,956 Speaker 3: when they float above the region where we want to 274 00:15:07,996 --> 00:15:10,796 Speaker 3: hold them as ion, we send another laser beam that 275 00:15:10,876 --> 00:15:14,156 Speaker 3: removes an electron from each atom. We know exactly how 276 00:15:14,156 --> 00:15:16,356 Speaker 3: to do that, very efficient and bam, it's now an 277 00:15:16,356 --> 00:15:18,876 Speaker 3: ion and it says, hey, wait a minute, I'm now stuck. 278 00:15:19,836 --> 00:15:22,436 Speaker 3: So they just sit there and we do something called 279 00:15:22,516 --> 00:15:24,636 Speaker 3: laser cooling to bring them to rest. 280 00:15:25,076 --> 00:15:29,796 Speaker 2: Sogerat to be clear now that so it's an ion 281 00:15:29,956 --> 00:15:35,036 Speaker 2: of uterbium and it's held because by electrical charge. That's 282 00:15:35,076 --> 00:15:36,676 Speaker 2: your Cubit you got a cubit. 283 00:15:36,756 --> 00:15:37,196 Speaker 3: Now that's it. 284 00:15:38,076 --> 00:15:41,516 Speaker 2: Okay, So that part you've solved, right, Yeah. 285 00:15:41,356 --> 00:15:44,076 Speaker 3: And when you put many turbium mindes next to each other, 286 00:15:44,076 --> 00:15:47,316 Speaker 3: they form a little crystal, an atomically perfect crystal. And 287 00:15:47,356 --> 00:15:49,396 Speaker 3: you can see that when you shine a different laser on, 288 00:15:49,636 --> 00:15:51,636 Speaker 3: they glow and you can see like stars in the sky, 289 00:15:51,756 --> 00:15:53,876 Speaker 3: there's they're not randomly oriented there. 290 00:15:53,956 --> 00:15:56,356 Speaker 2: So now you've created a bunch of cubits. You've got them, 291 00:15:56,396 --> 00:15:59,556 Speaker 2: as you say, like stars in the sky. They're sitting there. 292 00:15:59,596 --> 00:16:02,436 Speaker 2: They're held in place by electrical charge. What has to 293 00:16:02,436 --> 00:16:02,916 Speaker 2: happen next. 294 00:16:03,076 --> 00:16:05,716 Speaker 3: What people might not know is that an atomic clock 295 00:16:05,876 --> 00:16:09,076 Speaker 3: is actually based on two levels inside of the caesium atom. 296 00:16:09,196 --> 00:16:10,356 Speaker 3: It doesn't matter what the atom is. 297 00:16:10,436 --> 00:16:12,756 Speaker 2: Oh shit, I was already on uturbium. 298 00:16:12,356 --> 00:16:16,116 Speaker 3: And we have very similar levels in utbium that behave 299 00:16:16,156 --> 00:16:19,236 Speaker 3: as our cubit. It's a pretty good atomic clock, very 300 00:16:19,276 --> 00:16:24,556 Speaker 3: well defined states. And each each atom has its own cubit. Okay, 301 00:16:25,116 --> 00:16:27,676 Speaker 3: so we can prepare them all in the state zero. 302 00:16:27,956 --> 00:16:30,276 Speaker 2: So what is it? I mean? I know an atomic 303 00:16:30,316 --> 00:16:32,436 Speaker 2: clock is just a clock that's super accurate, But why 304 00:16:32,436 --> 00:16:34,236 Speaker 2: does that matter here? I don't even know what it means. 305 00:16:34,236 --> 00:16:36,596 Speaker 3: On. Ah, Well, it has to do with the fact 306 00:16:36,596 --> 00:16:40,316 Speaker 3: that two states in an atom, they have they generally 307 00:16:40,316 --> 00:16:43,356 Speaker 3: have different energies, sort of like different orbits planets around 308 00:16:43,356 --> 00:16:43,676 Speaker 3: the sun. 309 00:16:44,236 --> 00:16:48,156 Speaker 2: Okay, so it's like what level, what energy level is 310 00:16:48,156 --> 00:16:50,116 Speaker 2: the electron at it's going between one. 311 00:16:49,996 --> 00:16:52,236 Speaker 3: And you can think of that, and those energy levels 312 00:16:52,236 --> 00:16:55,516 Speaker 3: are incredibly well defined and they're exactly the same for 313 00:16:55,676 --> 00:16:57,036 Speaker 3: two different atoms. 314 00:16:57,596 --> 00:17:00,236 Speaker 2: Okay, and so is this our zero in one? Tell 315 00:17:00,276 --> 00:17:01,396 Speaker 2: me this is our zero and one. 316 00:17:01,436 --> 00:17:01,756 Speaker 3: That's it. 317 00:17:02,196 --> 00:17:06,956 Speaker 2: Okay. Uh So now we have our and if we're 318 00:17:06,956 --> 00:17:10,676 Speaker 2: not looking, they're in superposition. It's always some probability were 319 00:17:10,756 --> 00:17:11,316 Speaker 2: zero and one. 320 00:17:11,356 --> 00:17:13,916 Speaker 3: We start by preparing them all in a very boring state, 321 00:17:13,956 --> 00:17:17,916 Speaker 3: all in the state zero. That's like initializing the systems, 322 00:17:17,956 --> 00:17:20,396 Speaker 3: like clearing out your computer. It's putting all the registries 323 00:17:20,396 --> 00:17:24,836 Speaker 3: into zero. Reboot rebooter, that's rebooting. Okay. After we prepare 324 00:17:24,836 --> 00:17:27,196 Speaker 3: in zero, now we're going to make superpositions. We're going 325 00:17:27,276 --> 00:17:32,196 Speaker 3: to different laser beams, going to drive the system halfway 326 00:17:32,796 --> 00:17:35,036 Speaker 3: to the other level. That's sort of making a fifty 327 00:17:35,036 --> 00:17:37,796 Speaker 3: to fifty superposition. You can make as you can also 328 00:17:37,956 --> 00:17:40,956 Speaker 3: entangle them, and the entanglement is based on the fact 329 00:17:40,956 --> 00:17:44,076 Speaker 3: that these are ions, and they're like masses connected by springs. 330 00:17:44,076 --> 00:17:47,596 Speaker 3: They vibrate together. So when you push on one, literally 331 00:17:47,636 --> 00:17:51,196 Speaker 3: we push them in space. We push them around, and 332 00:17:51,236 --> 00:17:54,116 Speaker 3: they interact with their neighbors, and they're very well defined 333 00:17:54,116 --> 00:17:55,596 Speaker 3: ways to do this. Those are called gates. 334 00:17:55,796 --> 00:17:58,876 Speaker 2: Like I'm with you. When you've got your ions, I 335 00:17:58,956 --> 00:18:01,276 Speaker 2: understand you're resetting them and they have their zero in 336 00:18:01,316 --> 00:18:03,996 Speaker 2: one and then you do something with them, you mess 337 00:18:04,036 --> 00:18:06,636 Speaker 2: with them in such a way that they become entangled exactly. 338 00:18:07,076 --> 00:18:10,116 Speaker 3: Yes, okay, shine lasers that shun these atoms just a 339 00:18:10,156 --> 00:18:10,516 Speaker 3: little bit. 340 00:18:10,596 --> 00:18:12,916 Speaker 2: Love it. I love it that it's another laser. And 341 00:18:12,996 --> 00:18:15,396 Speaker 2: so now do you have a quantum computer? Have you now? 342 00:18:15,716 --> 00:18:15,956 Speaker 2: In this? 343 00:18:16,156 --> 00:18:19,116 Speaker 3: No? One? Last step? Okay, it's an easy one. It's 344 00:18:19,156 --> 00:18:22,636 Speaker 3: very similar to remember the initialization step. We prepare everything 345 00:18:22,676 --> 00:18:26,716 Speaker 3: in the state zero. The final step is to make 346 00:18:26,756 --> 00:18:29,356 Speaker 3: a measurement. Well, that's the beauty of atoms in a 347 00:18:29,436 --> 00:18:33,036 Speaker 3: vacuum is that we can send yet another laser beam, 348 00:18:33,356 --> 00:18:35,876 Speaker 3: very similar to the other ones. And this laser beam, 349 00:18:36,036 --> 00:18:38,276 Speaker 3: if the atom is in the state one, it will 350 00:18:38,276 --> 00:18:40,756 Speaker 3: glow and we can collect that. It's like a star. 351 00:18:40,916 --> 00:18:43,356 Speaker 3: It's really bright. You can see a single atom with 352 00:18:43,396 --> 00:18:46,996 Speaker 3: your naked eye in my laboratory. If it's in the 353 00:18:46,996 --> 00:18:49,596 Speaker 3: state zero, it's dark. So we basically look for bright 354 00:18:49,676 --> 00:18:52,596 Speaker 3: dark bright dark, and that's what we read. That's it. 355 00:18:52,756 --> 00:18:53,676 Speaker 3: That's a quantum computer. 356 00:18:54,836 --> 00:18:57,636 Speaker 2: And so you have built one of those, built. 357 00:18:57,436 --> 00:18:59,996 Speaker 3: Several of them, Duke, We have six of them at 358 00:19:00,036 --> 00:19:02,156 Speaker 3: I and Q. We've built nine different generations. 359 00:19:02,596 --> 00:19:05,436 Speaker 2: And the issue is they're just not big enough. They're 360 00:19:05,436 --> 00:19:07,116 Speaker 2: not enough cubits to be that. 361 00:19:07,356 --> 00:19:09,556 Speaker 3: Yeah, we're at twenty to thirty right now. We need 362 00:19:09,596 --> 00:19:11,156 Speaker 3: to get to sixty two hundred. 363 00:19:11,356 --> 00:19:17,596 Speaker 2: So as you've described it sounds easy. I get it, Like, 364 00:19:17,756 --> 00:19:19,676 Speaker 2: if you can do twenty, why can't you do sixty? 365 00:19:20,236 --> 00:19:24,556 Speaker 3: Okay, I'll make it very short. Remember the vibration I 366 00:19:24,636 --> 00:19:27,796 Speaker 3: talked about, like when you move one atom, the other 367 00:19:27,836 --> 00:19:30,876 Speaker 3: one moves. If you put five hundred of these atoms 368 00:19:30,876 --> 00:19:36,716 Speaker 3: in a chain, that motion becomes very sloppy and noisy. 369 00:19:36,876 --> 00:19:38,356 Speaker 3: So you want to limit the number you have in 370 00:19:38,396 --> 00:19:40,996 Speaker 3: a chain. We know we can put twenty or thirty, 371 00:19:41,076 --> 00:19:43,916 Speaker 3: maybe forty in a chain, but we need to we 372 00:19:43,996 --> 00:19:46,836 Speaker 3: need to have a modular way to connect to another 373 00:19:46,876 --> 00:19:49,756 Speaker 3: group of twenty or forty using optical fibers. We know 374 00:19:49,796 --> 00:19:50,516 Speaker 3: how to do that too. 375 00:19:51,436 --> 00:19:53,316 Speaker 2: We have done it, but you haven't quite worked out 376 00:19:53,356 --> 00:19:55,436 Speaker 2: all the bugs yet. Okay, so it's not there. Doesn't 377 00:19:55,476 --> 00:19:58,196 Speaker 2: need to be some big breakthrough or some step functions in. 378 00:19:58,316 --> 00:20:00,636 Speaker 3: The engineer just have to want it's engine a lot 379 00:20:00,676 --> 00:20:04,916 Speaker 3: of engineering, and we don't need breakthroughs. We don't need breakthroughs. 380 00:20:07,956 --> 00:20:09,996 Speaker 2: We'll be back in a minute with the lighting ground. 381 00:20:19,236 --> 00:20:21,836 Speaker 2: Back to the show. I know you got to go soon. 382 00:20:22,156 --> 00:20:23,956 Speaker 2: I want to finish with a lightning round and we 383 00:20:23,996 --> 00:20:25,636 Speaker 2: can truly make it a lightning round a lot of 384 00:20:25,716 --> 00:20:27,556 Speaker 2: questions and you can answer them fast so you could 385 00:20:27,556 --> 00:20:31,396 Speaker 2: go to your next meeting. I understand you're a percussionist 386 00:20:31,596 --> 00:20:34,516 Speaker 2: in an orchestra and that you play like the weird instruments. 387 00:20:34,556 --> 00:20:34,716 Speaker 3: Right. 388 00:20:35,796 --> 00:20:38,476 Speaker 2: I watched a YouTube video. I'm curious, what is your 389 00:20:38,596 --> 00:20:40,796 Speaker 2: favorite weird percussion instrument. 390 00:20:41,076 --> 00:20:43,116 Speaker 3: I'm gonna have to say, alephone. 391 00:20:44,756 --> 00:20:45,996 Speaker 2: What's the aleophone? 392 00:20:46,356 --> 00:20:48,276 Speaker 3: It's a wind machine? 393 00:20:49,276 --> 00:20:50,796 Speaker 2: How does it sound? What sound does it make? 394 00:20:51,796 --> 00:20:55,316 Speaker 3: Actually, some orchestras serve pieces called for it. It's basically 395 00:20:55,316 --> 00:20:57,676 Speaker 3: a big piece of burlap on a spindle that has 396 00:20:57,716 --> 00:21:03,876 Speaker 3: slats and it's like I made one of those for 397 00:21:03,956 --> 00:21:05,236 Speaker 3: our orchestra those fun. 398 00:21:06,436 --> 00:21:09,116 Speaker 2: So how long have you been working on quantum computer? 399 00:21:10,516 --> 00:21:13,276 Speaker 3: Thirty years a long time? 400 00:21:16,036 --> 00:21:19,516 Speaker 2: Did you think there would be a useful quantum computer 401 00:21:19,956 --> 00:21:22,436 Speaker 2: sooner than there has been? Like? How is it relative 402 00:21:22,476 --> 00:21:23,676 Speaker 2: to your initial expectations. 403 00:21:23,796 --> 00:21:27,196 Speaker 3: What I've learned is the love that you know. Physics 404 00:21:27,196 --> 00:21:31,436 Speaker 3: in the laboratory is one thing. Engineering is yet another thing, 405 00:21:31,876 --> 00:21:35,596 Speaker 3: and then product is a third thing, and they're all different. 406 00:21:35,636 --> 00:21:37,916 Speaker 3: And when I started in the field, I had no 407 00:21:37,996 --> 00:21:40,876 Speaker 3: knowledge of product and a little bit of knowledge of engineering. 408 00:21:41,436 --> 00:21:45,036 Speaker 3: I think given engineering and product nature of this of 409 00:21:45,076 --> 00:21:50,396 Speaker 3: this evolution, it's actually been faster than I thought it 410 00:21:50,396 --> 00:21:50,756 Speaker 3: would be. 411 00:21:52,276 --> 00:21:55,436 Speaker 2: I'm curious just in terms of your work in quantum physics, right, 412 00:21:55,476 --> 00:22:00,276 Speaker 2: this is you as physics professor. Now, when you're deep 413 00:22:00,356 --> 00:22:03,476 Speaker 2: in quantum physics work, does it ever freak you out 414 00:22:03,596 --> 00:22:07,076 Speaker 2: that quantum physics suggests that the world is so different 415 00:22:07,476 --> 00:22:09,236 Speaker 2: than the world we experience in our daily. 416 00:22:10,476 --> 00:22:12,716 Speaker 3: I should be losing more sleep over it, But I 417 00:22:12,716 --> 00:22:16,356 Speaker 3: think I've been able to be kind of successful by 418 00:22:16,436 --> 00:22:19,196 Speaker 3: not thinking, at least during the day of those things. 419 00:22:19,236 --> 00:22:21,436 Speaker 2: You're too busy trying to build a computer to think 420 00:22:21,436 --> 00:22:22,036 Speaker 2: about that stuff. 421 00:22:22,316 --> 00:22:24,036 Speaker 3: We know the law I'm more of a mechanic. I've 422 00:22:24,036 --> 00:22:26,556 Speaker 3: always been very good at applying math, and to me, 423 00:22:27,076 --> 00:22:29,676 Speaker 3: that's sort of what quantum is. Just it works. We 424 00:22:29,716 --> 00:22:31,356 Speaker 3: know the laws, don't think too much. 425 00:22:32,436 --> 00:22:34,676 Speaker 2: You mentioned when you go home you think about it, 426 00:22:34,676 --> 00:22:36,156 Speaker 2: Like when you wake up at four in the morning, 427 00:22:36,316 --> 00:22:40,396 Speaker 2: is there a particular aspect of the quantum universe that 428 00:22:40,436 --> 00:22:41,036 Speaker 2: you returned to. 429 00:22:42,516 --> 00:22:47,716 Speaker 3: Yeah, it's certainly entanglement that it's sort of space seems 430 00:22:47,716 --> 00:22:50,476 Speaker 3: to wind upon itself. I guess that's one way to 431 00:22:50,476 --> 00:22:51,036 Speaker 3: think about it. 432 00:22:51,236 --> 00:22:54,676 Speaker 2: Entanglement shouldn't that shouldn't happen, right, Like that's basically what 433 00:22:54,716 --> 00:22:58,916 Speaker 2: Einstein said, and like he seems right, or there's some 434 00:22:59,076 --> 00:23:01,556 Speaker 2: huge thing about the universe that we obviously don't understand. 435 00:23:01,796 --> 00:23:02,476 Speaker 2: I guess that's the other thing. 436 00:23:02,556 --> 00:23:05,356 Speaker 3: It's so fundamental too, you know that. I mean, what 437 00:23:05,436 --> 00:23:08,996 Speaker 3: is gravity. There's no microscopic model for gravity. It's just 438 00:23:09,636 --> 00:23:13,436 Speaker 3: space is distorted so that things sort of fall toward 439 00:23:13,476 --> 00:23:17,956 Speaker 3: each other. So and entanglement. It's really tantalizing to link 440 00:23:17,996 --> 00:23:21,516 Speaker 3: those two. Entanglement to gravity. It hasn't happened yet, but 441 00:23:21,556 --> 00:23:23,636 Speaker 3: that you know, that's an outstanding question. A lot of 442 00:23:24,276 --> 00:23:27,156 Speaker 3: really smart people are thinking about this. Yeah, that keep 443 00:23:27,436 --> 00:23:29,116 Speaker 3: I think about that sometimes it's fun. 444 00:23:34,956 --> 00:23:38,076 Speaker 2: Chris Munroe is the co founder and chief scientist at 445 00:23:38,156 --> 00:23:42,316 Speaker 2: ion Q. Today's show was produced by Edith Russello and 446 00:23:42,356 --> 00:23:45,436 Speaker 2: Gabriel Hunter Chang. It was edited by Sarah Nix, and 447 00:23:45,476 --> 00:23:48,596 Speaker 2: it was engineered by Amanda ka Wong. You can email 448 00:23:48,676 --> 00:23:51,876 Speaker 2: us at problem at pushkin dot fm, or you can 449 00:23:51,916 --> 00:23:54,956 Speaker 2: find me on Twitter at Jacob Boldstein. I'm Jacob Boldstein, 450 00:23:54,996 --> 00:23:57,196 Speaker 2: and we'll be back next week with another episode of 451 00:23:57,236 --> 00:24:03,356 Speaker 2: What's Your Problem.