John Martinis: The Nobel Physicist Behind Macroscopic Quantum Tunneling - #566

John Martinis won the 2025 Nobel Prize in Physics for proving macroscopic quantum tunneling is real. Less than a year later he’s telling why he left Google’s quantum computing team to start over. Subscribe if you want the physics and the politics of building the impossible. Martinis is the co-founder of Colab and one of the physicists who proved ordinary quantum rules apply to macroscopic systems. He built his career on the same Josephson-junction hardware his Nobel is built on, then led Google’s superconducting-qubit effort, the same team behind Google’s 2019 quantum supremacy claim, before an internal reorg pushed him out. We go into Anthony Leggett’s challenge to Schrödinger’s cat, what decoherence in quantum mechanics really means, and whether quantum computing is the first technology ever born from pure theory rather than experiment. We also cover the internal Google reorg that pushed Martinis out and what he learned about building something new inside a large institution. Whether quantum mechanics applies to the macroscopic world and what it took to prove it Why Martinis thinks quantum computing may be the first technology born from pure theory, not experiment What negative authority means and why it matters for anyone building something new inside a large institution Whether the US can win the quantum computing race against China How Martinis thinks about quantum mechanics interpretations after spending a career inside the math “Always be on the lookout for the impossible, right?” John Martinis CHAPTERS 00:00 The Nobel call that almost wasn't 01:01 How his wife found out before he did 03:32 Anthony Leggett's challenge to Schrödinger's cat 05:53 Why a Josephson junction, not a quantum dot or trapped ion 07:45 Quantized oscillations: the “smoking gun” and Balmer's ghost 08:18 Measuring the system: the resonance experiment 11:21 Systematic effects: what separates a good scientist from a lucky one 13:42 The Ed Ohm story: the man who found the CMB and doubted it 15:01 Wigner's “unreasonably effective” math and the weirdest thing about QM 16:54 The transistor myth: chewing gum, coat hangers, and germanium 17:34 Microwave engineering meets quantum mechanics 19:26 Decoherence: the friction you can't live without 24:06 The heretical claim: does theory ever precede technology? 28:22 The “paper qubit” problem 29:34 What quantum computers are actually good for 32:27 Should quantum computing be regulated like AI? 33:35 US vs. China: the quantum computing race 35:44 Collapse, Copenhagen, or many worlds? Martinis's answer 37:43 Leaving Google: “essentially demoted” 40:48 Why Colab exists and what “negative authority” means 42:50 The real bottleneck: funding, not physics 43:31 Final advice: always be on the lookout for the impossible Qolab: https://qolab.ai/ Get the transcript, fascinating bonus content, and my Monday M. A. G. I. C. Message: https://briankeating.com/yt Have a .edu email and live in the USA? You automatically win a meteorite: https://BrianKeating.com/edu Subscribe: https://www.youtube.com/DrBrianKeating?sub_confirmation=1 Support Into the Impossible on Patreon, get my weekly M. A. G. I. C. Message, unfiltered bonus content, and live monthly Office Hours with me: https://www.patreon.com/drbriankeating Join this channel for perks, monthly Office Hours, and your name in the Member Roster at the end of every episode: https://www.youtube.com/channel/UCmXH_moPhfkqCk6S3b9RWuw/join My books: Losing the Nobel Prize (memoir): http://amzn.to/2sa5UpA Think Like a Nobel Prize Winner: https://a.co/d/03ezQFu Focus Like a Nobel Prize Winner: https://a.co/d/hi50U9U Galileo's Dialogue (first-ever audiobook): https://a.co/d/iZPi9Un Twitter/X: https://x.com/BrianKeating Substack: https://briankeating.substack.com Blog: https://briankeating.com/blog Audio-only: https://briankeating.com/podcast Landing page: https://awake-mill-k25t.here.now #intotheimpossible #briankeating #JohnMartinis #NobelPrize #quantumcomputing #physics #podcast Learn more about your ad choices. Visit megaphone.fm/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:02Speaker 00

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• 1:00Brian Keating?

  Today we're joined with one of my heroes. It's not every day you get to talk to somebody who not only is such a great contributor to physics and has been inspiring not only the work that I do, but my whole collaboration is basically enabled by work that John and his collaborators did over the years. But he's also, as we say, a mensch. He's known for his teaching, for his group building. You're just kind of the physicist physicist. So, thank you for joining us.

• 1:25Speaker 04

  Well, that's very kind. Not everyone feels that way, but I appreciate the kind words.

• 1:31Brian Keating?

  You're now the 26th Nobel Prize winner I've had on the podcast. Every nine multiples of nine, I write a book featuring wisdom and I hope the third version will come out with you in the coming years. Well, I'll let you know about how that progresses. But I want to take us to that October morning last year. I was teaching quantum mechanics that day, advanced quantum mechanics with perturbation theory. And I said, "A guy I know just won the Nobel Prize." What was that like? What was the second thing that went through your mind when you got the phone call? Whatever time it was.

• 2:01Speaker 04

  Well, I actually didn't get the phone call. The phone is way across the house. But my wife was up late reading and she heard the phone ringing, but she figured she'd get it in the next day. She looked at her email and there was a bunch of congratulations. So, she knew about it, but she knows that I need my sleep, especially the next day when you have to be on the whole day. So, she waited till about 6 o'clock. There were reporters who showed up soon after that. So, it was actually better because my wife woke me up. But she was very clever about it. She tapped me on the shoulder and said there were reporters

• 2:46Speaker 04

  coming over. And I realized, "Oh, it's the beginning of October." So, I opened my computer and saw that. Let me share something a tiny bit personal. There are things called Nobel symposiums where they look at a field and see if the field is noteworthy and look at people and leaders in the field and the like. So, you kind of understand a little bit that you might be on some kind of list. Okay? For me, that's the biggest honor because the Nobel Prize is just so crazy unlikely, right? Just being invited to that is really very special.

• 3:26Speaker 04

  And then for some years, I'd wake up in beginning October. It's like, "Oh, okay." And it's just so wrong to be disappointed by this. So, after the years, I just stopped kind of... I knew, "Well, it's beginning October." But I stopped really thinking about it. That's why my wife didn't know. We didn't talk about this at all, right? Because it's just, "Okay, whatever happens." And it's actually better that way.

• 3:53Brian Keating?

  Yeah, there's a joke I sometimes will pull out on October 1st at 2:00 in the morning. I'll say, "I'm working on my best Swedish accent to cause somebody I don't like a heart attack. We are calling from the Swedish Royal Academy."

• 4:05Speaker 04

  Yeah, I've heard people get pranks like that.

• 4:07Brian Keating?

  Well, yours isn't a prank. And the only thing that frustrated me is that I was talking about quantum tunneling, but I was talking about single electron tunneling and even nuclear tunneling. So, you wanted for macroscopic tunneling. What was the impetus for... Obviously, you didn't set out to win a Nobel Prize. Talk us through the history of why you thought macroscopic effects would manifest themselves instead of just the already mysterious microscopic tunneling effects.

• 4:32Speaker 04

  Yeah, so this experiment and line of research was very much motivated by Anthony Leggett. You can just go back to the Schrödinger cat paradox where you do a microscopic atom decay that's connected up. So, the atom decays, it kills the cat. And then, okay, before you open the box, is the cat in some dead and alive state? And, okay, I think for me, there are ways to answer this that are very sensible. But Leggett pointed out that there actually is no experimental evidence that macroscopic entities, especially a cat, can obey quantum mechanics. And he said, "If there's no evidence, we should be looking for evidence as a way to

• 5:16Speaker 04

  test quantum mechanics." And he came up with the idea of these superconducting circuits where you have a macroscopic number of electrons that are tunneling through the junction. For me, as a young student, you look at quantum mechanics. It's really wonderful. My personal hobby was electronics, like John's Clark's group, because he was doing things on quantum noise, okay, and thinking about this. And for me, it was the most natural experiment to want to do. I'm surprised that there weren't 30 other groups doing it. At the point now, everyone can understand that. But back in the mid 80s,

• 5:55Speaker 04

  the idea of quantum information and doing these tests wasn't as popularized as it is now. So, for me, it was the most fascinating experiment. I thought it could be done cleanly. Obviously, John Clark was moving in this direction. Michel Devere came over. And for me, it was a perfect thesis experiment. And I'm going to say it was also very groundbreaking because then John's group, we understood how to measure noise in these devices. But to build a system and engineer it and think about the physics, combining microwave

• 6:36Speaker 04

  engineering and quantum mechanics and figuring out how to deal with the noise and the like to build a clean experiment was just really fundamental and groundbreaking. And of course, I find that wonderfully exciting, okay, to just try to figure all that out.

• 6:54Brian Keating?

  Why did you start off with a Josephson junction? Maybe first we'll explain what it is and keep in mind, my audience is highly technical, very competent. And I've tried to have Brian on the podcast as a fellow Brian. He's gone in interesting directions, shall we say, in consciousness and other kind of fields, very different from what he did as a young, very young man when he won the Nobel Prize for his work. But tell us, why Josephson junction? Why not a quantum dot or trapped ion? What made you start with that?

• 7:19Speaker 04

  Well, first of all, the Josephson junction is a macroscopic system where you have a macroscopic number of Cooper pairs, electrons, paired electrons, tunneling through the device. And to test the idea of whether macroscopic variables obey quantum mechanics, you need that. A quantum dot and atom, they're kind of single atomic systems, whereas this was very clearly macroscopic. And that's why Leggett proposed it. And that being in the superconducting field with John Clark's group, that's of course why we did it. Now, at the time, we didn't know if the Josephson junction was a clean

• 8:03Speaker 04

  system. In many physical systems, especially a macroscopic system, there can be dirt effects, other things that go wrong that may cause it not to work as well as you would like. And at the time, we didn't know any of that, so we just forged ahead. But I would say the reason I'm talking to you today about the Nobel Prize is it turned out that it was a clean system. And this was figured out by many, many people over decades of work, testing it. I mean, we made the foundation for understanding how to do that, but building these systems properly took a while for a whole lot of people to figure out.

• 8:44Brian Keating?

  What strikes me as so magical and beautiful is that you guys ended up seeing discretization and quantization and spectral features. And it's exactly reminiscent of what Ballmer saw 60 years before the invention of quantum mechanics. Have you ever thought about what it was like to be him grappling with something that wouldn't be determined or even predictable for many decades? Did you ever have that kind of inkling of like, "We're in this weird, mysterious territory"? Or was it, "If we keep putting one foot in front of the other, we're going to get to some goal that we've set out for ourselves"?

• 9:18Speaker 04

  That's a really great question because the way we were thinking about it and we started it, John Clark's a serious experimentalist and I was a new student. But what he and we decided very early on is we had to measure the parameters of the system in order to do a careful test of the theory. And the obvious thing to do was to put on microwaves and have a resonant phenomenon and see that resonant phenomenon as a way to measure the oscillation frequency of the system, which is a very fundamental parameter. And what was interesting is classically...

• 10:00Speaker 04

  I set up an analog simulator in about a, I think, a day or two and put in noise and then showed that indeed you can see some kind of resonant effect. So very early on, even though we knew about that, we had to do tests in doing it. Now, of course, you know, as we did this, we were quite interested in what would be the quantum effects. Now, what happens classically, both in an atom and in our system, is that this oscillates in this nonlinear well, it has a spectrum of frequencies, one frequency when it's low and a lower frequency

• 10:38Speaker 04

  when it's high. So just like when people talk about electrons circulating the nucleus, classically, there's a range of frequencies that it would emit light over. Of course, what you saw was quantized energy levels and quantized light, which, you know, it was clear we could see in the system. So I would say the fact that you see quantized oscillations is a key feature of quantum mechanics. And I think that what we were able to see is like the smoking gun thing that you're doing that. Now, it could be

• 11:19Speaker 04

  that you have to realize, if you're really being careful about this, it could be that there's resonances in the circuit you're connecting it to. So you have to be careful about, you know, claiming that. And that's why we did a bunch of experiments detailed that are in the papers, but no one ever talks about, to say that we had a well-defined experiment without these resonances. The resonances we saw made sense in terms of the physics of the of the system and the like. But in the end, that was a key observation. Now, of course, what was also interesting is Leggett talked about what happened to tunneling when you had dissipation. That's very new physics, which you normally don't see in

• 12:02Speaker 04

  electrons and nucleus. And eventually, we were able to do those experiments really well and show that that theory made sense, too. So there is a whole series of things we were able to do because it was really well engineered, good connection of microwave engineering to quantum mechanics.

• 12:21Speaker 00

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• 12:50Brian Keating?

  One of the things I love to point out to my younger, you know, listeners, readers, and viewers in my books, when I interview, you know, titanic physicists such as yourself, is when you do the thing that you really didn't think you would have to do, you just mentioned it, you can have this collective phenomena from alternative effects rather than the thing you're quote unquote looking for, and those are called systematic effects. And I typically tell my students, anyone can get the right answer, you know, we can get the Hubble constant, you know, and it could be beautiful. But the real determinant of whether or not you're a good scientist is how you account for the things that you could be wrong about, right?

• 13:27Speaker 04

  Yeah, exactly. You know, and the fundamental thing about nature is you can never prove anything about nature. You can disprove your theories, but you can never prove it because something else could be explaining it. But what you do as an experimentalist is measure enough parameters and do enough of the check experiments that if it's another theory, it would have to be really kind of, you know, a crazy, not simple theory. And that's what you do. And that's, for example, why we were measuring the parameters. Okay. The other thing to realize, and I talk about, I like to explain this to the students, is in the

• 14:08Speaker 04

  beginning, we did some experiments at, you know, 1 Kelvin to 4 Kelvin to see what was going on. And the data didn't make sense at all. And it was because we were seeing noise. And very early on, we just did something, we compared it in a way that was really kind of tricky at the time and didn't make sense. And then we started saying, well, okay, we're gonna have to filter it right and the like. And once we understood the microwave engineering, microwave filtering, we redesigned the experiment pretty quickly, and then all the data started making sense. Okay. So there were some internal checks that you, you know, you have to look at very carefully. There were a few prior experiments that hadn't really done that

• 14:52Speaker 04

  properly. And I think the physics community appreciated all those checks and being able to do a beautiful experiment because of that. And, you know, all, good experiments are like that. They're well designed, and then you think about things can go wrong, and you figure that out.

• 15:12Brian Keating?

  Yeah, reminds me, there was a scientist named Ed Ohm, who worked at Bell Labs on the exact same Hohmdel antenna as Penzias and Wilson, you probably know this story. And he actually measured the CMB, and he attributed it to a systematic error. He basically said it's a systematic error, it's excess noise, or all the atmospheric contributions add cumulatively and they don't cancel out. And then Penzias and Wilson said, well, let's do a calibration, let's measure that with a liquid nitrogen chopped Dickey switch load.

• 15:38Speaker 04

  Yeah, yeah.

• 15:39Brian Keating?

  That won them the Nobel Prize. But he had actually discovered it, you know, three years earlier in the same data. But that's, that's exactly right. And what you said is so important that we can't prove things as physical science. We're not mathematicians. You know, mathematicians can prove one plus one equals two. It takes 200 pages of piano algorithms and all these other things. But it kind of reminds me of what Eugene Wigner, another Nobel laureate, said once. He said, the mathematics is sort of unreasonably effective. And, and I think about that, and I kind of have narrowed it down. I say that the square root is unreasonably effective because in classical mechanics, you can make the Poisson bracket, you can make the commutator of momentum and position, right? And it's zero, right? It doesn't matter if you measure momentum first or position first, it gets there. But

• 16:20Brian Keating?

  if you add the square root of negative one, you get the Poisson bracket for the Heisenberg relationships, and those do not commute, right? What's the weirdest thing about quantum mechanics to you?

• 16:31Speaker 04

  The weirdest thing, it's really a complicated phenomenon. And it takes into at least your third year, gypically, as an undergraduate, and then you take it more. And I'm gonna say after doing this for many decades, I kind of understand it fairly well at this point. But, you know, it's complicated, but at the same time, there's this mathematical edifice where you can understand it well. And, you know, it's the basis of many fundamental standards. So it's extremely accurate, too. It's both complicated but understandable, unintuitive, but given enough time, to me, it's intuitive right now. It's kind of strange.

• 17:13Speaker 04

  And, you know, that, it's just a very deep theory. And it's kind of amazing that nature works, you know, at this, this very, very deep level. And like I said, the other thing is, which is what our Nobel is about, it's not just the physics of the small or fundamental particles, it's actually a generic physics that everything can obey. It's just really hard for ordinary objects to get into some parameter space where you can see it. So it's actually a generic phenomenon that's all, you know, that potentially could be all around us.

• 17:49Brian Keating?

  And tunneling is that way, too. And what really kind of surprised me about ordinary, you know, kind of electron tunneling, is we have this kind of myth in both technology and in pure science that you look into the equations and then you invent the technology, right? So like, you know, Bardine and the transistor, we couldn't have invented it unless we understood quantum mechanics. When in reality, I think, I mean, you know this much better than me, and I want to get your opinion. But, you know, kind of, if you look at the first transistor, it looks like, you know, a chunk of rock, like the germanium, and a chewing gum, and a coat hanger, and it's all putting, I want to ask you, we're gonna talk a lot about quantum computers in a little bit.

• 18:24Speaker 04

  Oh, and by the way, our first experiment in Berkeley was carefully designed, okay? And, you know, but if you look at what's being made now, it's, you know, it's like, it's like the Bell Labs transistor. But, you know, there's some physics there, okay? But that's what you have to do when you're first exploring something, is you do some experiment that's kind of minimal and you can get it to work. And then once you understand that the principles behind it, you can then engineer it and look deeper and deeper into it. And that's what's beautiful about physics, is there's all these levels that you have to understand to get it to work.

• 19:04Brian Keating?

  What's been the most, you know, kind of enabling technology on the step, you know, contributor to the work that you did? Was it the, you know, advances in superconductors? Was it, you know, the kind of fluxonion, the 3D cavities? What kind of like stepping stones on the way to the revolution that you guys worked on and still do work on? What was the most important keystone?

• 19:24Speaker 04

  So what happened at the time is that we understood that this was a microwave experiment. And we went to the astronomy department and got their S parameter meter and started understanding and reading microwave books. And in the end, what we did and the field did is combine the concepts of microwave engineering with the concepts of quantum mechanics. And it's interesting because microwave engineering has wave phenomenon and resonance like quantum mechanics does. So they're actually somewhat close. I also always think that you can understand

• 20:06Speaker 04

  about 80, 90% of our superconducting quantum devices with microwave engineering. And then you have to throw in quantum mechanics at the appropriate point to do that. It kind of reminds me, you have Maxwell's equations, but in terms of understanding electrical circuit and like, you use circuit diagrams, okay? And what you've done is you've taken something very complete and almost abstract, and then brought it down to a level where we can do complex engineering with it. And that's kind of what we were able, what we started in that experiment. And of course, we explored that for many decades. And now, you know,

• 20:49Speaker 04

  we're doing it. And we're still, I'm still exploring that in terms of materials and other concepts that we have here.

• 20:56Brian Keating?

  Yeah. And, you know, kind of makes me think about a statement I think you made once, you know, that people seem to hate decoherence until they need it. So without decoherence, like friction, you know, if you've ever, you know, kissed a, kissed a loved one, right? You need some friction, right? Life wouldn't be fun without friction. But but tell me, is decoherence necessary, you know, for these devices? Or is it purely a nuisance that must be obliterated?

• 21:21Speaker 04

  I'm gonna say decoherence is always here in the real world. And the problem is if you take the Schrodinger equations, that's just, you know, a pure, simple physics without any decoherence. And of course, people know how to put in decoherence and do that. And it's kind of like, you know, how do you understand thermodynamics without, you know, entropy? Okay, you know, you have the basic equations which are conservative, and then you introduce entropy, and then you could see the real world. And this is what happens with quantum mechanics. And also for quantum computing, it first, it's, it's a very practical

• 22:02Speaker 04

  important thing, because it limits your quantum computer. But also, when you start doing things like measuring real circuits, and let's say, doing error correction, in error correction, you're removing the randomness or the entropy of that. And in some sense, you need decoherence. And I would say decoherence, in my view, is kind of tied to how things get measured. Okay. And if you look at Exploring the Quantum by Ramond and Harosch, it gives you a good description of that. That's very integral to quantum mechanics. It sounds like the ugly side of it, but it's actually a quite important part of it.

• 22:42Brian Keating?

  And at some level, we have to always connect to the classical world, right? So there's inevitability of dealing with classical effects. And so how do you guard against, you know, kind of these systematic biases? Like for us, just take measuring a superconductor, right? So if you want to measure the superconductor, you could be very careful, you could do all the four-point measurements you like. And you probably have been in a lab with my late great friend, Paul Richards, from UC Berkeley. And he was just the most careful person. And he wouldn't let you do a measurement, you know, that wasn't at least four points in its design. But at some level, you know, can you actually prove that these things have zero resistance in the junctions? Can you prove, you know, that the flux is purely being, you know, quantized in the way that the, you know, Leggett and other equations suggest that they are? Or do you always have to, ah, we kind of have to, we know it's

• 23:26Brian Keating?

  not purely quantum mechanical, because we have to connect to these devices? Or is it truly manifest that they behave as they should be purely quantum mechanically?

• 23:34Speaker 04

  It's always a matter that there are certain limits where the flux will jump, okay? And you could be, let's say, near to the transition temperature, and then, and then you'll see that flux is not quantized, or at least it jumps in its quantization. Physicists have been exploring this for a long time. In fact, the experiment I did in the 80s was all about how, you know, when you put a current up to the critical current, at the critical current, it then looks like a normal metal. So it's superconducting. And then when you hit the critical current goes normal. Well, it happens a little bit before that, either doing the thermal fluctuations, or due to macroscopic quantum tunneling.

• 24:19Speaker 04

  And, you know, it's an example of physicists understanding the limit. Now, you can look at the limits of these various things, and you can understand that it should be exponentially small. For example, where a superconductor, there are things, excitations called quasiparticles, that you limit the superconductivity, but there's a gap, and it's even minus delta U over K T. And if you do the calculation, that's tiny. But the problem is, is you have stray infrared light in a real experiment, and then generates the quasiparticle. So it's not exponentially small. So I would say, you know, physicists are great at figuring

• 25:03Speaker 04

  out all these details and figuring out what's wrong. And over the years, then, you know, this is why it took, you know, decades to figure all this out. Lots of experiments happened, looking at all the details, and not just taking the pure theory, but thinking about all the possible ways that things can go wrong. And then you engineer around it. For the infrared case, you'd have to do very careful shielding, which we didn't do at first. And then we realized we had to do that. And then there's still a little bit of residuals, but we can deal with that.

• 25:36Speaker 00

  The action's on the court. And as the official beer sponsor of the NBA, Michelob Ultra is getting fans closer to the game with a chance to win courtside seats, merch, and more. Visit michelobultra.com/courtside to enter. Michelob Ultra Courtside, 26 to 27. No purchase necessary. Open to US residents 21+. Begins on October 1st, 2026, and ends on June 30th, 2027. Multiple entry periods. See official rules at michelobultra.com/courtside for free entry, entry deadlines, prizes, and details.

• 26:05Brian Keating?

  So I want to make a fairly heretical claim, and then I want you to demolish it and put me in my place. But my, my claim is that no one's ever looked at an equation and out pops a technology from purely contemplating it, except perhaps quantum computing. We'll get there in a second. But if you look at the transistor I just said, you know, they, they weren't like looking at, you know, the, the Schrodinger equation, saying, oh, we're going to get this technology if we put the chewing gum, the coat hanger, and the, you know, piece of germanium together. MRI came, you know, from Bloch's equations being, being understood. Laser maser came from population inversion, which was Townsend's kind of guess. Is the quantum computer perhaps the first technology in history that really came from the equation outward? Or is it going to be, you know, sort of along the lines of, of,

• 26:50Brian Keating?

  as I said, you know, the high temperature superconductor? Really, we didn't understand the theory until, you know, my late great professor, Leon Cooper, right? What do you make of this claim that I'm making? That we don't look at the, into the equations, and then the technology comes out. We experiment, guess, and then eventually technology comes, and then we backfill in the explanation.

• 27:06Speaker 04

  I haven't studied this, and it sounds like you've had. But I've been said, talked to, I've talked to theorists about this. And they say it's very rare that a theory kind of precedes an experimental observation. And the one example they give is the Josephson effect, where Brian Josephson, you know, understood this. And, and, you know, basically, you have to do the calculation to second order in order to understand what the superconductivity does. But the way this all came about, it was very murky at the time. And, you know, if you look at it, John Bardine gave Brian Josephson a very hard time with this, which

• 27:48Speaker 04

  is actually kind of amazing, because superconductivity and BCS is a second order calculation, okay? People hadn't put that all together at the time. So that was one of the few times, I'm sure it's not the only one, but the few times where it preceded it, and the theorist was given a hard time. But of course, he, the Nobel Prize, that meant that it was very strange. And I would say quantum computing, I hadn't thought about that. But I'm, that's right. This came from very theoretical concepts. And then, you know, people work through it experimentally, once, you know, they understood it would be interesting to do that. Let me

• 28:28Speaker 04

  tell you what the problem with quantum computing is, is if you abstract it away to qubits...

• 28:36Speaker 04

  Okay, you abstract away to idealize qubits and the Schrödinger equation, and then it looks very simple and very nice, okay? But the problem is, real experimental systems are much more complicated. There's all these dirt effects. And it's kind of easy to think that, okay, you can just build that without having to go through and all the, you know, understand what's going on. So I like to say the best qubit out there is what I call the paper qubit, a theory qubit. And it's only by doing the experiments do you know that everything is wrong, everything's wrong with it. And it usually takes decades to figure this out. Okay, it's not magical thing.

• 29:21Speaker 04

  The other thing is, a lot of the efforts are actually headed by theorists. If you, if you look at it, not all of them, but a lot of them are. And that's because it's very easy to abstract this away. I actually think, again, history will borne this out. I actually think that this is a little bit of a problem because in actually to build a thing requires you to, you know, really understand all the problems. Okay? So by abstracting all the problems away, you can be very optimistic and, you know, do things. But it's only, you know, going into lab and realizing what all the problems are

• 30:03Speaker 04

  and then fixing them that you can actually build it. Because physical qubits are not perfect by any means. Some people claim that their technology is great. There are always problems, okay? That's the way that nature wants to fight back. But I think in the end, we can, we can fight back harder.

• 30:22Brian Keating?

  Yeah, now I want to talk about quantum computing. And again, I tend to be a little more cheeky and provocative, so don't be afraid to, you know, put me in my place. But in 1981, you know, Feynman didn't say quantum computers are going to replace, you know, your desktop, your MacBook, your laptop, your Chromebook, whatever. He said, "Nature is quantum, so we should probably be using, you know, quantum systems to do computation." I always joke, and I've done work with a firm called Quantum Rings, which does a lot of software and simulations of quantum mechanical computers. But I kind of joke sometimes that, you know, quantum computers are the best system to model how quantum computers work. A, and then, you know, they're good.

• 30:58Speaker 04

  Quantum systems in general, yes.

• 31:00Brian Keating?

  Quantum systems. But it's not clear, you know, sort of like an answer, you know, to a question maybe. And again, I'm saying this with, with probably lack of humility. But what are quantum computers really going to be good for? And you can't use the words, you know, cryptography, and you can't use Lagrangians, or material science, or quantum computers. So outside of that incredibly impressive domain of portfolio, I mean, it's like if you said, "My computer can only be used for doing, you know, spreadsheets, word processing, and, and internet browsing, right? I mean, it could do a lot more, general computers. So what can a quantum computer do besides those three things that are very important and very hyped up?

• 31:35Speaker 04

  Yeah, I'm really interested, partly because I'm a physicist, okay? Is quantum computers modeling, simulating other quantum systems? And, you know, there's a huge amount that it can help with there. Because right now, a lot of classical computers or supercomputers are used to do so. And, you know, you can only model something so big before you run out of memory, because quantum computing is hard and run out of speed. Okay? And then you have to do approximation methods, which are fantastic. But, you know, they only work. And in fact, a lot of it is that, you know, certain approximations work for this problem and that problem. And you have to compare with physical systems to kind of choose that.

• 32:20Speaker 04

  It's a little bit cheating, but, you know, okay, it's very practical and that's good. That's what I'm, I'm really interested in. And, you know, just the example, I don't know if this is a good example, but we all are interested in rare earths now. Let's say for electric motors and electrification and transportation system, et cetera, et cetera. But they're rare, and there's a supply chain issue there. And I'm sure ecologically, there could be issues with that. If you could use not so rare earths, let's say by inventing a new chemical or process, or maybe make it more ecological to mine, that's a huge benefit to society. And you could say the same things with drug discovery and other things.

• 33:04Speaker 04

  I think this is actually a big application, if you like, endemic industrial applications. But that's more how regular computers got started. And then over time, I can imagine there could be other things, let's say for optimization. It's not so clear. There's a killer application for that. Okay, a lot of people are looking at, a lot of people are claiming things. It's not clear whether a clever classical optimization would be good. So it kind of can be a little bit like AI, where people try various things for decades before coming on some, you know, the right way to do it. I also looked at as very important. So, you know, it, it's, it's a powerful computing engine.

• 33:49Speaker 04

  And it's going to take a while to figure it out. And, you know, the, the quantum computers we can build right now are, are too small. If we can make them bigger and then help with the theorists to inventing the clever algorithms, I feel, you know, very confident we can do something with this. But the big problem is we're trying to compute, compete against these huge data centers, okay? Which are getting huger and huger as every day. Eventually, the exponential power of a quantum computer can overcome that. We just have to make it big enough and be clever enough for the algorithms.

• 34:27Brian Keating?

  Yeah, that's right. And that's what you and our mutual friend Alan Ho introduced me to you and as co-founder of your company, Colab. We'll get to that in a second. But now I want to take kind of the pushback on myself. You know, I'm kind of, you know, maybe bipolar this morning. But, but now I'm going to make the argument that these things are incredibly powerful and perhaps with great power. I just talked to the foremost AI safety researcher in the world, Roman Yampowski, who coined the term AI safety. And he basically says, "Superintelligence is either almost here or about to be here, and it's uncontrollable, it is unaccountable, it is unverifiable. We have no control over what we just created." So I want to make that argument for quantum computers. And then I want to take us back to, you know, like 1947.

• 35:10Brian Keating?

  You know, the government didn't let, you know, Oppenheimer set up Oppie's atomic bomb company, you know, just selling his own little portable nuclear device. Or he kept it classified. And, and, you know, should they be classifying? You know, is it okay that Google, IBM, and even Colab? You know, hopefully you're going to be just as big as that, right? So tell me, make the argument, why shouldn't you be regulated right now before the genie escapes the bottle, as it has for superintelligent AGI?

• 35:36Speaker 04

  First of all, we're going to learn a lot from superintelligent AI. And that's the immediate issue to deal with. And that's here, and it's coming. And, you know, I agree, people should be thinking about this. I think we're going to learn from that, okay? And we should take the lessons from that and then figure out what we're going to do. The problem with quantum computing is, it's just not here yet. And yet there's this big race. And to be honest, the race is the US versus China. You look at the papers from China, they know what they're doing. It's a, it's a serious race. Developing kind of in the wild is actually an efficient way to, you know, get things done.

• 36:20Speaker 04

  Just like with AI happened, okay? Now, there was a secret program within the government for quantum computing. But that's not where the biggest developments happened. I don't think I have to explain that to readers, okay? And, you know, it's just that, you know, this, this competitive landscape, I could just call it savage capitalism, okay? Actually, it's pretty efficient if you want to do that. In fact, I argue that the way that the projects in China is operating is maybe more savage than the capitalism in the US. I, I don't know all the details, but it could be. These are very good questions, and I, I'm concerned.

• 37:04Speaker 04

  But, you know, on the other hand, we're, we're trying to develop it in our own, in our own particular way. And, but we're being very careful about who we do. We know that, for example, the US government is going to want us to build our quantum chip in the US. And that's how we're organizing the way that we do that. Some of the other more classical control that can be done worldwide with our good diplomatic partners. And, you know, we're, we're being a little bit careful about that. But I think it's, you know, it's the Google and IBMs and others where they're really on the forefront. And I'm sure there's a lot of discussion that goes on there.

• 37:47Speaker 00

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• 38:14Brian Keating?

  Now, I can't resist asking you this question. I mean, you're the ideal person to ask. You've probably collapsed more wave functions than any human in history. What do you think is happening, John? Is it a collapse? Is it Copenhagen? Is it some non-unitary evolution? Is it a many worlds branching? Tell me about your epistemology. What are you thinking when you do these measurements?

• 38:34Speaker 04

  I explicitly dislike the many worlds interpretation because it sounds very Trumpian in the sense that you're generating real estate that's doing that. So.

• 38:49Brian Keating?

  Who never thought of that? But now he's gonna, now he's gonna make a.

• 38:52Speaker 04

  In a humorous manner, but I'm very much thinking that, you know, the measurement and the dissipation and the decoherence is what's giving you the state collapse. And again, if you look at exploring the quantum, they have a very nice elegant way to talk about how these things called pointer states are exponentially sensitive to decoherence. And a small amount of decoherence can collapse you into these measurement states. And for me, that's the clearest explanation around. I know some people don't like that and that's fine, but that's the way that I view it.

• 39:31Brian Keating?

  Jim Peebles once told me to shut up and measure when I asked him about some, some aspect of.

• 39:36Speaker 04

  If you shut up and measure, we wouldn't have done that experiment or people would. So, so these are good questions. You need to do the experiments. And like in the exploring the quantum, they did very nice experiments to flesh out what the theory was and to argue that this is what's going on. So I think it's important to study this and understand that. But for me, this is a question that has been answered via decoherence phenomenon. It's just like not understanding entropy and thermodynamics. So to me, it's the same kind of understanding.

• 40:13Brian Keating?

  Take us back to the, you know, the quantum supremacy and you had achieved this incredible result for the first time, but you soon after left Google. I'm curious, was that a blessing in disguise? I mean, it led you to co-found a company with Asan Allen Ho and others. It's such a brilliant idea, this company. The point is the divorce from Google, would you be willing to talk about that? We don't have to, but.

• 40:34Speaker 04

  You know, after that experiment, Google decided to reorganize. And instead of being congratulated for leading this project, I was essentially demoted. Okay. And there were reasons for that that we don't have to get into. And I tried that for about nine months and, you know, basically I went from the head of the hardware to let's say one over N authority. It was a very much a socialist thing, but I actually found I had negative authority after that. And if you want to understand negative authority, just think about when you had teenagers. Okay. That's your negative authority.

• 41:15Speaker 04

  And frankly, I don't think the people in Google thought that I was that technically competent. I was okay, but you know, you, you, you can tell when people feel that way. And it was just time to leave. And, and what happened is that was definitely lemons. Okay. I still regret everything that happened, but it's what happened. But what I would say is working with Alan and then Robert, we figured out, well, what is it we really wanted to do? Not, you know, next year or to meet the next milestone, but if we wanted to build a million qubit quantum computer, what would we have to do? And we really focused on the qubit manufacturing and the wiring and scaling up.

• 41:57Speaker 04

  And we came up with a series of ideas and we published a paper on that. We started a company and we're feeling really good about this. And we're doing something that's really different than everyone else. That's exciting. And our view is that when we get this to work, it's very foundational shift to the field, which is great. You know, that's what you want to do is do something important. On the other hand, it's risky because the general consensus out there is that you need to fabricate the qubits with this liftoff process because it's much cleaner and the like, whereas you do a complicated deposition and etch, you have problems.

• 42:38Speaker 04

  That's the thing. And what we figured out is that's kind of right, but you have to fabricate it in the proper way and then you can get it to work. And, you know, we've kind of have figured out what that proper way is. And we're working very hard to do the steps that you need to, to make it very clean. And, you know, in the end, semiconductors are, no one uses liftoff. I mean, this is just, doesn't work. You use deposition and etch, but of course, I don't know, there's billions, trillions of dollars figuring out how to get that to work. We think we understand enough now to be able to do that on a modest startup economy.

• 43:18Brian Keating?

  I think your approach is, is, is so fascinating. It's a sort of a 3D printing, but you know, massive scale. My teenager made this for me. That's one of the few things that he does for me with my negative authority.

• 43:28Speaker 04

  Look, you know, young people want to do their own things. I get it, you know? And they want to break through from their family, which is what Google, what happened at Google. Normally the kids leave the house to break through and they don't kick the parents out of the house. But okay, you know, that was the easier thing for Google to do. And I understand that I had done things that the Google people, I'm too much like Elon Musk to work at Google. Okay. Put it that way.

• 43:58Brian Keating?

  Well, I just note that it was exactly at that time that they went peak woke. And, and within a few months, they had things like you ask it to create a picture of the founding fathers of America. And it was like Violet Davis, you know, Violet, the black and, and white hair and all sorts of interesting features.

• 44:14Speaker 04

  Well, you know, for example, all the, the co-writers of the, um, the attention paper, which was the big breakthrough, they all left Google. I think there, there are different reasons, but there are similar reasons. And, you know, it's not a surprise that certain people don't fit into a corporate environment. They're more entrepreneurs and I'm very much an entrepreneur. And what I've been able to do is I've been able to kind of unleash my creativity in a private company. Now, we don't have the money. I think I could be way more productive at Google, but if that's not the way they want to run it, then, you know, it's great to be doing this in your own company.

• 44:56Speaker 04

  And, you know, in our company, we can set our culture and set what we do.

• 45:01Brian Keating?

  What's the limiting factor just on a technical side? I mean, we have a dilution fridge. We don't use it that often. We have deposition facilities here. What's your limiting, you know, kind of pacing item that, that is, you know, kind of an obstacle, but, but you're going to overcome it? If I gave you 10,000 dilution fridges, if I gave you unlimited time with 300 millimeter wafers, what do you need, John?

• 45:20Speaker 04

  You need refrigerators to do a lot of testing, but you also need professional fabrication facility where you can do rapid turnaround. And then the third thing you need is a principled understanding of what's going wrong. Right now it's a little bit, you know, just people try things. However, I think we have a principled understanding now, so we have to work on the other two. And, you know, obviously take more data and the like. It's all of the above. In the end, I'm just going to say in the end for us, it's funding. Because with more funding, we'd buy more dilution refrigerators and we could work with the companies and pay for having a bigger effort.

• 46:01Brian Keating?

  One final question is just related to the title of the podcast. The only way to know the limits of the possible, Arthur C. Clarke said, is to go beyond them into the impossible. John, what one piece of advice, you had 20 seconds with your 20-year-old self, what would you give the advice to him to go into the impossible with the courage that you've had over your career?

• 46:18Speaker 04

  Well, what happens is you're a scientist, you're always working on projects. There are projects that are kind of incremental and you know what to do and you're going to advance your field and whatever, but always be on the lookout for the impossible, something new, something other people don't think will work. That if it's, it does work, it's very foundational and change the field. Now you'll have to curate those ideas really well because most of your ideas aren't going to work out. And I have ideas all the time and I curate them and then you choose the best ones and try it. Our company, Colab, is what everyone thinks is not the right way to go.

• 47:00Speaker 04

  I've thought about it carefully. We understand why it could work and it's looking good. But you have to think very carefully about it. But yeah, always be on the lookout for the impossible, right?

• 47:13Brian Keating?

  I love it. I'm going to make that the motto of the show. John Martinis, winner of the 2025 Nobel Prize in Physics. Thank you so much for being an inspiration. You're just a physicist, physicist. John, thank you so much. Have a great weekend. We'll talk again soon.

• 47:28Speaker 05

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• 47:54Speaker 06

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