Speaker 1: Hey, welcome to Sign Stuff, a production of iHeartRadio. My
Speaker 1: name is Jorge cham and to the end of the program,
Speaker 1: we are talking about a technology that may potentially impact
Speaker 1: the life of every single human on Earth. It might
Speaker 1: change how we protect data and come up with passwords,
Speaker 1: it might help us make new and exciting materials, and
Speaker 1: it might render cryptocurrencies like bitcoin and dotgecoin totally useless.
Speaker 1: I'm talking about quantum computers. What are they, how do
Speaker 1: they work? And most exciting is that we're going to
Speaker 1: get to visit one of them and actually hear it
Speaker 1: in action. So power up your curiosity, log in, and
Speaker 1: let's answer the question how do quantum computers work? Hey? Everyone? Okay,
Speaker 1: so when I started this episode, I was both terrified
Speaker 1: and excited. Terrified because explaining anything with the word quantum
Speaker 1: is really hard, but excited because I had heard that
Speaker 1: a friend of mine was making quantum computers just ten
Speaker 1: minutes from my house, and this was a great excuse
Speaker 1: for me to go take a look at them. So
Speaker 1: we're going to go see these quantum computers in person
Speaker 1: at the end of the episode, but before that, I
Speaker 1: wanted to make sure that I understood what they were
Speaker 1: how they work, and also what they're potentially going to
Speaker 1: be used for. So this episode is split into three parts.
Speaker 1: What is a quantum computer and how does it work?
Speaker 1: What are quantum computers for? And then we're going to
Speaker 1: go see the quantum computers and we're going to talk
Speaker 1: about how they're made and why they're so hard to
Speaker 1: get them to work. Our guide through all of this
Speaker 1: is going to be my friend who's making the quantum computers,
Speaker 1: Professor Oscar Pater. He's a professor of physics and applied
Speaker 1: physics at Caltech and he's the head of quantum hardware
Speaker 1: for Amazon. He does research on nanophotonics, quantum optics, and
Speaker 1: of course quantum computers. Here's my visit to Oscar Painter's lab.
Speaker 2: Ah, hey, Oscar, how are you good to see you
Speaker 2: after so many years.
Speaker 1: Yeah, it's been a while. Huh yeah, well thanks so
Speaker 1: much for talking with me.
Speaker 3: Yeah, it's been a while. Happy to try to fill
Speaker 3: you in on some of the things we've been doing
Speaker 3: in the areas of quantic computing.
Speaker 1: Okay, so the first thing I wanted to talk to
Speaker 1: him about was just what does the word quantum mean?
Speaker 1: Because I feel like we're going to need that to
Speaker 1: understand what a quantum computer is. Now, the word quantum
Speaker 1: is the word we used to describe how things behave
Speaker 1: at the level of atoms and the tiny little particles
Speaker 1: that make up the atoms. So in our everyday lives,
Speaker 1: we're used to things being solid and us being able
Speaker 1: to hold them, like, for example, if you take a
Speaker 1: piece of wood or a ball. But if you take
Speaker 1: that piece of wood or ball and you chop it up,
Speaker 1: and you keep chopping it up, you get down to atoms,
Speaker 1: and then you'll notice that those atoms don't behave in
Speaker 1: the same way that a piece of wood or a
Speaker 1: ball do. Here's how Oscar explains it.
Speaker 3: It turns out that down to the microscopic scale, so
Speaker 3: not our everyday scale of things, the laws of physics
Speaker 3: that dominate in that regime is quantum mechanics, and quantum
Speaker 3: mechanics is a theory that has some strange attributes that
Speaker 3: we don't experience every day. For example, it postulates that
Speaker 3: things can be in superposition, so you can have objects
Speaker 3: being in sort of what we think of as two
Speaker 3: distinct realities at the same time. Imagine having a particle
Speaker 3: in one position and another position simultaneously. That seems very
Speaker 3: odd to us, but in quantum mechanics it's very natural.
Speaker 1: Like, for example, I grabbed this piece of wood in
Speaker 1: front of me, and it's a piece of wood. It's
Speaker 1: not two things at the same time. Right, It's in
Speaker 1: one location.
Speaker 3: Right, it's sitting there. It's firmly right in front of you.
Speaker 1: Right. If I had an atom in front of me
Speaker 1: or an electron, it wouldn't exactly.
Speaker 3: You would find that if you repeated the measurement or
Speaker 3: finding its position multiple times, you might find that, Oh,
Speaker 3: I get this weird outcome that sometimes I measure it here,
Speaker 3: sometimes I measure it there. And that's because it's actually
Speaker 3: in many places at once, all right, And that's fundamental
Speaker 3: to the description of quantum mechanics. The way I like
Speaker 3: to think about quantum mechanics is really as waves and amplitudes.
Speaker 3: So think about you're at a pond and you throw
Speaker 3: a rock in a pond, and you see this ripple
Speaker 3: of the rock. Right, That's how I think about, Like
Speaker 3: the rocks are sort of the particles, and these wave
Speaker 3: phenomena are sort of the actual physical quantum mechanical description
Speaker 3: of that particle.
Speaker 1: Like the particle the thing, the atom or the electron.
Speaker 1: It's not the rock you throw into the pond, no,
Speaker 1: but it's actually the ripple of the ripple.
Speaker 3: Yeah, that's right, it's this wave. So I may have
Speaker 3: started with something that was very local, like that rock,
Speaker 3: but then it becomes very quickly it sort of propagates
Speaker 3: out and is actually better described as this wave on
Speaker 3: the pond.
Speaker 1: Because like a ripple and a wave in a pond
Speaker 1: like that, it's kind of in a lot of places
Speaker 1: at the same.
Speaker 3: Exactly, that's right. And then the interference is important to understand.
Speaker 3: If I throw two rocks in the pond, then I
Speaker 3: see the sort of interference of the ripple patterns coming
Speaker 3: from each rock that blashed in the pond.
Speaker 1: Right, Like each ripple starts at simple, but then they
Speaker 1: start to mix together and form this complex pattern on
Speaker 1: the surface of the pod.
Speaker 3: Exactly, like how do they evolve in time?
Speaker 1: Okay, so when you get down to the level of atoms,
Speaker 1: things behave really strangely. Scientists think of things at that
Speaker 1: level not as little tiny balls, but as waves or
Speaker 1: ripples of energy, like the ripples in a pond. Now
Speaker 1: you may think, wait a minute, if things are kind
Speaker 1: of wavy and strange at the level of atoms. Why
Speaker 1: isn't it that way when you get to big stuff
Speaker 1: like a piece of wood or a ball, And the
Speaker 1: answer is that they are that way. There's just a
Speaker 1: lot of atoms in a piece of wood, and from
Speaker 1: a distance, it gives you the impression that it's solid.
Speaker 1: It's sort of like how some clouds from afar they
Speaker 1: might look solid once you get up close to them,
Speaker 1: they're actually kind of fuzzy and wispy, and all the
Speaker 1: water droplets are moving around. So that's quantum. Now. A
Speaker 1: quantum computer is what happens when you make a regular computer,
Speaker 1: but you make the circuits out of individual atoms or
Speaker 1: particles like electrons.
Speaker 3: Classical computers are formed from things that are very very
Speaker 3: classical in nature.
Speaker 1: And they uperate kind of on hard switches.
Speaker 3: Yeah, like, yeah, that's right, the transistors on your phone,
Speaker 3: And that's what we call these types of elements. The
Speaker 3: transistors are used to store information or perform calculations, and
Speaker 3: the transistors are really set by a bunch of electrons
Speaker 3: in part of the circuit. And usually you're talking about
Speaker 3: quite a few electrons.
Speaker 1: Because regular transistors are huge. They're bigger than an atom.
Speaker 3: Yes, exactly, that's physically what's going on in your phone.
Speaker 3: And what I'm telling you is that the way to
Speaker 3: think about it is in the quantum case, I just
Speaker 3: have one electron.
Speaker 1: Like the circuits are made out of individual electrons.
Speaker 3: Yeah, atoms is exactly what you're doing. Or a quantum
Speaker 3: particle doesn't have to be electrons, can be other particles.
Speaker 3: That was the sort of very early idea from people
Speaker 3: like FIM and others back in the nineteen eighties is
Speaker 3: if you're going to do this, and you better make
Speaker 3: them out of quantum mechanical objects to begin with.
Speaker 1: Okay, So if you make a computer where the circuits
Speaker 1: are made of individual quantum objects like atoms or electrons,
Speaker 1: then you get a quantum computer. And what that does
Speaker 1: is that it makes their calculations also quantum mechanical. And
Speaker 1: this is where the concept of a cubit comes in.
Speaker 1: It's like a regular bit in your computer, and a
Speaker 1: bit is like a one or zero, but a cubit
Speaker 1: is a quantum mechanical one or zero.
Speaker 3: Classical computers are formed from digital bits and they go
Speaker 3: between one and zero. A quantum computer doesn't have these
Speaker 3: hard zero one states. It has every possibility in between.
Speaker 3: So imagine if we have these two states zero in one.
Speaker 3: I told you that a quantum system can be in
Speaker 3: two different states at once, right, So it can be
Speaker 3: in zero and one at the same time, and I
Speaker 3: can have a different weight of zero or one at
Speaker 3: the same time. It could be ten percent zero, ninety
Speaker 3: percent one.
Speaker 1: It's like a shade of gray.
Speaker 3: Yeah, And so you have all those possibilities in between.
Speaker 3: It can be zero or one or anything in between.
Speaker 1: It can be black, white, dark, gray, light.
Speaker 3: Gray, exactly, So it has all those shape in between.
Speaker 3: You can take zero with some fraction and add it
Speaker 3: to one with any other fraction. You can have any
Speaker 3: combination of that.
Speaker 1: So on a regular computer, if you multiply two bits together,
Speaker 1: it's like you're multiplying two fixed numbers together, like three
Speaker 1: times four. But in a quantum computer, when you multiply
Speaker 1: two cubits together, it's like you're multiplying two things that
Speaker 1: can be lots of numbers at the same time. So,
Speaker 1: for example, it's like you're multiplying every number from zero
Speaker 1: to one hundred times every number from zero to one thousand,
Speaker 1: all at the same time in one operation. That's what
Speaker 1: makes quantum computers unique. They take this weirdness of the
Speaker 1: quantum world and then let's you do math with it. Now, Actually,
Speaker 1: it's not doing all of those multiplications or calculations at
Speaker 1: the same time. It's more like how Oscar described it earlier.
Speaker 1: If you drop two rocks in a pond, you see
Speaker 1: the two ripples spread out and mix together to form
Speaker 1: a complex ripple pattern. That's more of the picture of
Speaker 1: what a quantum comp does. It doesn't do calculations with
Speaker 1: hard numbers. It does calculations with the ripples and patterns
Speaker 1: of quantum numbers. Of course, my next question for Oscar
Speaker 1: was what is that good for? Why would you want
Speaker 1: to do math this way? When we come back, I'm
Speaker 1: going to ask Oscar what quantum computers are for, and
Speaker 1: then at the end we're going to go check out
Speaker 1: the ones he's built. You're listening to sign stuff. Welcome back. Okay,
Speaker 1: to recap, we learned that a quantum computer is a
Speaker 1: regular computer whose circuits are made with individual atoms or
Speaker 1: small particles like electrons, and by doing that you can
Speaker 1: do quantum calculations. That is, you can do math, but
Speaker 1: with numbers that are actually lots of different numbers at
Speaker 1: the same time. So now the question is, why would
Speaker 1: you want to do that? What are quantum computers? Four?
Speaker 1: Here's more of my conversation, but quantum physicist Oscar Painter.
Speaker 1: Let's say it's a few years into the future and
Speaker 1: we have quantum computers, yes, in our phones, like I
Speaker 1: have one in my podget Okay, what can I do
Speaker 1: with it? And how is my life different?
Speaker 3: I think that's a very unlikely scenario.
Speaker 1: Okay.
Speaker 2: I think that's the wrong way.
Speaker 3: To think about how quantic computers might change our lives,
Speaker 3: at least as far as I can project into the future. Okay,
Speaker 3: I think the best way to think about a quantic
Speaker 3: computer as we envision it right now is that it
Speaker 3: will be more.
Speaker 2: Like a supercomputer.
Speaker 3: So a supercomputer is just a very large computer that
Speaker 3: can perform calculations beyond what our desktop, our personal computers
Speaker 3: can do. And these are usually very large, almost building
Speaker 3: scale computers and computer clusters that have many, many different
Speaker 3: processing units that are all integrated together, and through that
Speaker 3: scale you can perform a huge number of computations per
Speaker 3: second and therefore compute some of the hardest problems.
Speaker 2: That are out there.
Speaker 3: A lot of them are used for chemistry problems. They're
Speaker 3: used to study particle physics, so fundamental physics, trying to
Speaker 3: understand models of quantum particles that are beyond the current
Speaker 3: standard model. They're used to compute the properties of materials,
Speaker 3: climate modeling, and things like that.
Speaker 1: So usually science and tech, yeahs, And.
Speaker 3: There's always this competition between different nations who has the
Speaker 3: fastest or the biggest supercomputer.
Speaker 1: I see, So you envision quantum computers will be sort
Speaker 1: of like a specialized version of computer.
Speaker 3: It's going to be some very special type of supercomputer
Speaker 3: that can solve specific problems that quantum computers will be
Speaker 3: very effective at that we can't do today on classic computers,
Speaker 3: no matter how much we scale them up. And the
Speaker 3: key is it's not just a faster supercomputer. It performs
Speaker 3: calculations in a fundamentally different way, and therefore it can
Speaker 3: tackle problems that are possibly outside of the reach of
Speaker 3: these conventional classical supercomputers.
Speaker 1: What do you mean? Out of the reach meaning that.
Speaker 3: No matter how fast they get or how big they get,
Speaker 3: they'll never be able to compute some of these problems,
Speaker 3: never or take an infinite exactly, it's just the scaling
Speaker 3: is so bad for these problems, you would take way
Speaker 3: too long and require way too large on machine. So,
Speaker 3: no matter how hard we work on our current computing technology,
Speaker 3: it has limits and it's known and you can prove
Speaker 3: it for certain problems, and quantic computers when they looked
Speaker 3: at theoretically these same problems, they realize that the same
Speaker 3: restrictions or limitations for quantic computers are not there. There's
Speaker 3: examples where we believe and strongly believe that certain mathematical
Speaker 3: problems that are important are really really hard to perform
Speaker 3: and can't be solved using classical means, no matter how
Speaker 3: much we improve the technology.
Speaker 1: No matter if I have a building full of supercomputers,
Speaker 1: yeah exactly, you'll never be able.
Speaker 3: To just fill the world with them. You still won't
Speaker 3: be able to do it. Yet a quantic computer can
Speaker 3: solve it pretty efficiently.
Speaker 1: Well. Step me through some of these problems.
Speaker 3: Like so the example that everyone points to, and it
Speaker 3: is pretty amazing that people found this, But there's this
Speaker 3: mathematical problem. It just happens to be very applicable to
Speaker 3: our safety or security of our data. So it turns
Speaker 3: out that most of the security of all of the
Speaker 3: data that you hold, all the data that banks or
Speaker 3: various institutions around the world want to be safe and protected,
Speaker 3: they typically encrypt it. And those encryption techniques that have
Speaker 3: been used were what are called RSA encryption, where you
Speaker 3: want to take a large number and understand what its
Speaker 3: prime factors are.
Speaker 1: Okay, so the first big thing that quantum computers can
Speaker 1: be useful, the one that got people really excited about
Speaker 1: them in the nineties, is in breaking password encryption. So
Speaker 1: whenever you enter your password on a website or when
Speaker 1: you download your bank statement, that information is encrypted or
Speaker 1: scrambled so that if anyone happens to catch that information,
Speaker 1: they can't tell what it says. And the whole scheme
Speaker 1: is based on the idea that if I gave you
Speaker 1: a really large number, it's really hard to find what
Speaker 1: its prime factors are. Here's how Oscar explains it, but
Speaker 1: just to give you a quick heads up, a prime
Speaker 1: number is a number that can't be divided except by
Speaker 1: itself or by one. So, for example, thirteen is a
Speaker 1: prime number because you can't fight thirteen by anything except
Speaker 1: thirteen and one, And the same goes for seventeen nineteen
Speaker 1: twenty three and so on. Anyways, here's Oscar explaining it.
Speaker 3: So I give you a number and I say, tell
Speaker 3: me what the prime factors are, and you have to
Speaker 3: break it down to its prime factors. So you know,
Speaker 3: a simple one is, you know, like two, it's just
Speaker 3: one times two, one and two. Those are the two
Speaker 3: prime factors, right. But it gets harder as these numbers
Speaker 3: get bigger.
Speaker 1: If I tell you one millions be round there and
Speaker 1: forty three.
Speaker 3: Yeah, seventeen, very hard to actually answer what those what
Speaker 3: the prime factors are. But if I give you the
Speaker 3: prime factors, you can multiply them together and very quickly
Speaker 3: get the answer to what that larger number is.
Speaker 2: Right.
Speaker 3: And so if you know the prime factors, I can
Speaker 3: give you what they multiply to.
Speaker 2: But if you give me.
Speaker 3: The number that they multiply to without then I have
Speaker 3: a very hard time finding out what the prime factors are.
Speaker 1: Because you'd have to get kind of have to guess.
Speaker 3: Well, you know, there's mathematical techniques to try to find these,
Speaker 3: but they're very inefficient.
Speaker 2: And so it turns.
Speaker 3: Out that most of the security of the way we
Speaker 3: encrypt information is based upon that asymmetry. And how hard
Speaker 3: the problem is.
Speaker 1: So, now, let's say somebody has a quantum computer.
Speaker 3: Right, then they can find those prime factors and they
Speaker 3: can now decrypt all that information.
Speaker 1: They can just grab it from the air, yeah, and
Speaker 1: be like, oh, I know.
Speaker 3: And yeah, I can find the prime factors and then
Speaker 3: I can use that to decrypt the information.
Speaker 1: That would be easy for a quantum computer, and you
Speaker 1: just press a button and will tell you, oh, this
Speaker 1: is an oscar or his secret decoder.
Speaker 3: Yeah, exactly, So that would you know. That obviously concerned
Speaker 3: a lot of people when that algorithm was developed.
Speaker 1: Okay, this gets a little bit heavy into encryption and
Speaker 1: quantum algorithms, but the main point is that most of
Speaker 1: the security of our passwords and our sensitive information, and
Speaker 1: also the encryption of things like bitcoin and all those cryptocurrencies,
Speaker 1: they all depend on this one math problem which is
Speaker 1: really hard for regular computers even supercomputers to solve. And
Speaker 1: that is a problem of finding the two prime numbers
Speaker 1: that multiply to get a really large number. But then
Speaker 1: in nineteen ninety five, a computer scientist named Peter Shore
Speaker 1: publish the paper titled Polynomial time Algorithms for prime factorization
Speaker 1: of discrete logarithms. On a quantum computer, which essentially showed
Speaker 1: that if you have a quantum computer, you can solve
Speaker 1: this problem in a short amount of time. And this
Speaker 1: is probably the main reason that people have been rushing
Speaker 1: to make quantum computers since then, because imagine if everyone
Speaker 1: in the world, people, companies, countries are all protecting their
Speaker 1: secrets using the same trick, but you had a special
Speaker 1: quantum computer that could break that trick, you could rule
Speaker 1: the world. Now, the details of how Peter Shore's algorithm
Speaker 1: works are a little complicated to explain here, but the
Speaker 1: essence of it is that you're using the ripples on
Speaker 1: a pawn nature of quantum numbers on a quantum computer
Speaker 1: to basically try out every possible combination for how to
Speaker 1: break your secret encryption, and you use some clever math
Speaker 1: tricks so that these ripples combine and mix together until
Speaker 1: the right answer pops out. So that is the main
Speaker 1: reason that people are excited about quantum computers. But there
Speaker 1: are other reasons and other possible applications, So here's Oscar
Speaker 1: telling me about them.
Speaker 3: Another example is maybe more natural to think about, and
Speaker 3: this is where quantum computers were first proposed. It to
Speaker 3: be interesting or useful, and that is the simulation of
Speaker 3: nature itself. Nature as we know it is not classical.
Speaker 3: If you peel the layers of the onion enough and
Speaker 3: you get down to the core, right to the atomic scale,
Speaker 3: it turns out that the laws of physics that dominates
Speaker 3: quantum mechanics, okay, like the actual mathematics of that, when
Speaker 3: you describe it, when you have many particles, it quickly
Speaker 3: becomes something that you can't simulate with a classical computer.
Speaker 3: So all those interference of all the particles and keeping
Speaker 3: track of all of that. A classical computer, if you
Speaker 3: try to simulate that, you quickly run out of steam
Speaker 3: and it becomes an exponentially hard problem. And so you know,
Speaker 3: a classical computer is just ill suited.
Speaker 2: To doing that.
Speaker 3: But a quantum computer that's made out of the same
Speaker 3: those sort of particles that can do with that interference naturally,
Speaker 3: you know, has a natural advantage in terms of using
Speaker 3: it to simulate the natural world at its quantum mechanical core.
Speaker 1: Why would I want to do that?
Speaker 3: Yeah, So that's the questions like, okay, so that's great,
Speaker 3: but why would I want to do that other than
Speaker 3: maybe I want to understand physics better? Well, this idea
Speaker 3: that I want to understand how material behaves is a
Speaker 3: very good example. If I'm building an electrical circuit, or
Speaker 3: I'm building a new battery, or I'm building a different
Speaker 3: energy process inside of a material or energy storage device.
Speaker 3: A lot of times that depends on what the electrons
Speaker 3: are doing. If I want to understand or something unique
Speaker 3: when I describe them quantum mechanically, maybe there's special properties
Speaker 3: I'm just totally blind to. So if I wanted to
Speaker 3: make a better superconnecting material, something that can carry electricity
Speaker 3: with no resistance, right, maybe we can have magnetically livitated trains.
Speaker 3: Maybe you can have you know, really efficient electrical circuits
Speaker 3: that don't dissipate any energy.
Speaker 2: All of these things.
Speaker 3: Then I would have to use a quantum computer to
Speaker 3: model that behavior.
Speaker 1: And you said there's some maybe potential applications in chemistry
Speaker 1: and biology.
Speaker 3: Yeah, you know, if I think about what is going
Speaker 3: on when I have a chemical reaction, usually it comes
Speaker 3: down to the electrons, and I need to understand what
Speaker 3: they're doing in order to understand, you know, whether this
Speaker 3: chemical reaction is going to be efficient or not, or
Speaker 3: if I want to describe it with chemical accuracy, so
Speaker 3: I can use it to, you know, do some sort
Speaker 3: of industrial chemical process. The biological application. It's like, if
Speaker 3: I want to know how molecules are biologically relevant molecules
Speaker 3: lined together, then potentially I need to know more information
Speaker 3: about the electronic behavior in these molecules. If I wanted
Speaker 3: to do that without having approximation or much higher accuracy
Speaker 3: than a quantum computer would be potentially more capable.
Speaker 1: There I we might be able to predict better how
Speaker 1: a vaccine will work, or whether a certain chemical introduce
Speaker 1: in your body will.
Speaker 3: Right now, we don't have that sort of level of specificity.
Speaker 3: I mean, we'd love too. People are proposing techniques, but
Speaker 3: that's the right idea, by the devil's in the details.
Speaker 3: And you know, you have people saying, well, look, you know,
Speaker 3: I think even today there's I won't call them skeptics,
Speaker 3: but there's a lot of people that are saying, well,
Speaker 3: I can keep improving my classical algorithms, and whether you
Speaker 3: can really gain advantage from the quantum simulations is a
Speaker 3: it's a practical question, and maybe we don't have as
Speaker 3: clear an example or as clear a win when it
Speaker 3: comes to how quantum computers will will do better, or
Speaker 3: be more efficient, or be able to do the calculations
Speaker 3: fast or even do them ones that the classical computers
Speaker 3: can't do. But I think there's definitely something there. It's
Speaker 3: just that we still have to work on a quantum algorithms.
Speaker 3: It's not as clear cut, I would say.
Speaker 1: So those are the two main applications or uses for
Speaker 1: planted computers. One is in breaking encryption using a special
Speaker 1: algorithm called phase estimation that only works in a quantum computer,
Speaker 1: and the other is to simulate nature, because nature is,
Speaker 1: after all quantum at its core, and so scientists think
Speaker 1: that quantum computers will let us better simulate how atoms
Speaker 1: and electrons interact so that we can design better materials,
Speaker 1: better semiconductors, and maybe better medicines. Now, I said so far,
Speaker 1: because this is all still very new, and there might
Speaker 1: be other classes of problems like the encryption problem where
Speaker 1: quantum computers are just fundamentally and exponentially better at solving,
Speaker 1: but nobody knows for sure. Of course, it's all hinges
Speaker 1: on whether or not we can actually make quantum computers
Speaker 1: at the level that they would actually be useful and
Speaker 1: most important, reliable. So now we're going to go actually
Speaker 1: see these quantum computers that Oscar is building, and he's
Speaker 1: going to tell us why they're hard to make and
Speaker 1: why they're so prone to making errors. But first, let's
Speaker 1: take a quick break. You're listening to science stuff and
Speaker 1: we're back. Well I heard you have a quantum computer
Speaker 1: in your basement.
Speaker 3: Well not in my basement, but in my my laboratory. Yeah, here,
Speaker 3: can we go see it?
Speaker 2: We can?
Speaker 1: Okay, yeah, let's get see it.
Speaker 2: Okay, you want to do that?
Speaker 1: Okay, so where are we going?
Speaker 2: Just the next door.
Speaker 3: We don't actually even have to go down into.
Speaker 2: The basement, into the basement, no.
Speaker 1: Basement sound and more.
Speaker 2: Yeah, i'd scientists exactly.
Speaker 3: So let's all these labs have different variants of quantic
Speaker 3: computers that we're testing. Multiple quantum computers here, yeah, yeah,
Speaker 3: not just one. So there's small scale quantum computers, but
Speaker 3: the largest ones are you know, ones at at Amazon
Speaker 3: or Google or IBM or you know some of the
Speaker 3: other startup companies. These get to be maybe a factor
Speaker 3: of ten times larger than the ones I'll show you. Okay, okay,
Speaker 3: so this gives you an idea. All of these control electronics,
Speaker 3: right is to use to control about twenty of these
Speaker 3: quantum bits.
Speaker 1: There's twenty quantum meaning twenty particle. A machine made up
Speaker 1: of twenty quantum particles.
Speaker 3: Corract right, which we are manipulating as quantum bits, and
Speaker 3: that circuit lives down inside of this special refrigerator.
Speaker 1: Okay, So if you've ever seen, or if you google
Speaker 1: a picture of a quantum computer, most likely what you
Speaker 1: see is something that looks like an upside down metal
Speaker 1: wedding cake with circular tears or platforms that get smaller
Speaker 1: and smaller as they hang down from the ceiling. That
Speaker 1: is basically a super intense refrigerator. The whole purpose of
Speaker 1: it is to get the tip of that upside down
Speaker 1: cake really really really cold.
Speaker 3: And this refrigerator is under vacuum, under high vacuum. It's
Speaker 3: a temperature which is about ten million degrees above absolute zero.
Speaker 2: Ten degrees.
Speaker 3: So to give you an idea, So if I go
Speaker 3: to the deepest part of space, it's a few degrees calvin,
Speaker 3: a few degrees above that food and zero, the coldest
Speaker 3: darkest parts of outer space or that universe. Yeah, but
Speaker 3: this thing's about thirty times colder than that.
Speaker 1: Even WHOA So would you say that some of the
Speaker 1: cold this places in the whole universe.
Speaker 3: I mean no, I mean you can get there's people
Speaker 3: that do this for a living that make really cold things.
Speaker 2: But this is among the very very coldest things. Okay, yeah,
Speaker 2: but this is extremely cold.
Speaker 1: What does it need to be cold?
Speaker 3: Because even the lights, even if we turned all the
Speaker 3: lights off, even just the fact that the room's hot, it's.
Speaker 2: Room temperature, but it radiates.
Speaker 3: Radiation, and that radiation would completely destroy the information in
Speaker 3: the corner bit.
Speaker 2: I see. We have to get it really dark.
Speaker 3: We have to make sure that there's not any of
Speaker 3: this thermal energy that's making it into the circuit, otherwise
Speaker 3: it'll destroy the manipulation of those quantum parties. And so
Speaker 3: it has to be as isolated as we can from
Speaker 3: the environment. We would ideally seal it off from everything,
Speaker 3: so it would be like zero temperature and there would
Speaker 3: be nothing coming in other than what we want to
Speaker 3: send to it to control it.
Speaker 2: And then you can see there's all of these cables,
Speaker 2: uh huh. Each of these feeds.
Speaker 3: Into a microwave cable that could use to control individual
Speaker 3: quantum bits or quantum particles on the circuit.
Speaker 1: So what I'm looking at is a room full of
Speaker 1: electronics and cables, and in the center is a massive
Speaker 1: structure with two suspended eye beams, and hanging from those
Speaker 1: beams is the upside down wedding cake I mentioned before,
Speaker 1: which in this case is sealed inside a really thick
Speaker 1: metal cylinder, and inside that cylinder at the very tip
Speaker 1: of the wedding cake cool to almost the coldest anything
Speaker 1: can be in the whole universe. Is a little chip?
Speaker 1: Good a quantum computer?
Speaker 2: Well?
Speaker 1: What's in there? So describe me what's inside the core
Speaker 1: of it? Is it like a little chip? Yeah?
Speaker 2: Like love.
Speaker 3: It's what's called a superconnecting quantum circuit. So it uses
Speaker 3: little metal traces on a silicon wafer that we pattern
Speaker 3: on the surface, and when you get them cold enough,
Speaker 3: they become super connecting, which means they can carry electrical currents.
Speaker 2: Without any energy dissipation.
Speaker 3: Okay, And it turns out that you can form these
Speaker 3: sort of quantum particles like these atoms, where the current
Speaker 3: is circulating in a clockwise way inside of a little
Speaker 3: tiny ring, or it's circulating counterclockwise, and the clockwise could
Speaker 3: be zero, when the counterclockwise could be one, and you
Speaker 3: can get in any superposition of these two circulation patterns,
Speaker 3: and I can use then I can manipulate what the
Speaker 3: superposition is, and I can have interact with other circulating currents.
Speaker 2: To the things in our circuit.
Speaker 3: There are a few hundred microns in size, so they
Speaker 3: might be a few times the human hair diameter, so
Speaker 3: they're pretty big relative to conventional transistors. It's made out
Speaker 3: of many atoms, but it behaves like a single atom.
Speaker 2: Okay, yeah, the way to think about it.
Speaker 1: So there's like a little array of these things, a.
Speaker 3: Little array of these things on the surface of a microchip,
Speaker 3: and then each of them we can control the current flow.
Speaker 3: So what are called single cubit gates. We bring them
Speaker 3: together and then let them interact them bring them apart.
Speaker 3: So I need to be able to manipulate the single particle,
Speaker 3: put it in any sort of superposition I want.
Speaker 2: And then you have to read out the state of
Speaker 2: these cubits too.
Speaker 3: You have to know after I do my computation, are
Speaker 3: you in state zero or state one? All right, I
Speaker 3: have to ask that question for all my cubits, and
Speaker 3: that will give me the answer.
Speaker 1: I see what is that hearing?
Speaker 3: So this is called the pulse tube cooler sownders sounds
Speaker 3: like if you were ever a kid growing up in
Speaker 3: the eighties and you watch Battlestar Galactica or the Cylons
Speaker 3: and Battlestar Galactica, they do they walk, and they would
Speaker 3: have this flashing light and they'd have this sort of
Speaker 3: sound coming from them.
Speaker 2: This is a similar sort of sound.
Speaker 3: This is a pulse tube cooler and it's shooting a
Speaker 3: slug of helium gas onto a cold plate and then
Speaker 3: in doing so, when it expands, it can cause cooling.
Speaker 3: It's analogous to what you do with the regular refrigerator.
Speaker 3: That's the first stage of cooling, though that only gets
Speaker 3: you down to maybe a tenth of the temperature of
Speaker 3: the room. And then if I want to go even
Speaker 3: cooler down and by another factor of ten or one hundred,
Speaker 3: then you have to use a recirculating gas.
Speaker 2: In this case, it's a dilution fridge that takes mixtures
Speaker 2: of isotopes.
Speaker 3: Of helium helium three and helium four, and when they mix,
Speaker 3: there's an entropy of reaction and that's what gets you
Speaker 3: down to this lowest temperatures I mentioned.
Speaker 1: So it's several stages. Something like take a fridge put
Speaker 1: it inside of another fridge.
Speaker 3: So there's actually like sort of three or four stages
Speaker 3: of if you're inside of a fridge and you have
Speaker 3: instead of the fridge, the one fridge is too hot
Speaker 3: for the other fridge, so we have to isolate them,
Speaker 3: and then we have to do that for every successive stage.
Speaker 1: It's like, if I take my freezer and I put
Speaker 1: it inside of like a restaurant freezer, just be colder.
Speaker 2: Yeah, okay, exactly, I keep doing that. I add, you know, another.
Speaker 1: Way, the fridge inside of my fridge have a restaurant freezer.
Speaker 3: And I keep you know, each of them has the
Speaker 3: ability to get colder and colder. Yeah, So you have
Speaker 3: to do it in stages. Otherwise, if you try to
Speaker 3: do a direct shot, it's too much of a thermal
Speaker 3: load on the system.
Speaker 1: I see. So that's a quantum computer in action. Most
Speaker 1: of what you see when you look at a picture
Speaker 1: of a quantum computer, it's all the machinery needed to
Speaker 1: keep the actual circuit in a near perfect vacuum and
Speaker 1: as cold as possible, and all of that is to
Speaker 1: completely isolate the quantum computer from the outside world. We'll
Speaker 1: get to why you need to do that with a
Speaker 1: quantum computer. But first I was curious how much a
Speaker 1: quantum computer like this costs. Here's what oscars it. Well,
Speaker 1: this is definitely much bigger than my phone.
Speaker 2: Yes, exactly.
Speaker 3: That's why I was saying, you're probably not going to
Speaker 3: carry one of these things around.
Speaker 1: How much is this something like this if I wanted
Speaker 1: to build one in my garage?
Speaker 3: Okay, Well, you know there's always a big difference between
Speaker 3: science money and money that you know, when you're talking
Speaker 3: about conservative products that have large volumes. I remember the
Speaker 3: first time we purchased a big piece of equipment from
Speaker 3: my lab when I was the first a faculty member.
Speaker 2: It was about the same.
Speaker 3: It was about smaller than this thing, so smaller than
Speaker 3: a few cubic feet, but it was more expensive than
Speaker 3: my house when I bought it.
Speaker 2: So there's a big difference. Cot So just keep that
Speaker 2: in mind.
Speaker 3: But one of these systems today, because it's very specialized,
Speaker 3: probably costs about a.
Speaker 2: Million dollars set up.
Speaker 3: Wow, that's another reason why you will probably wont carry
Speaker 3: it around in your pocket any times soon. But it's
Speaker 3: an important actually point to make, is that people will
Speaker 3: build these systems and go to the larger scales. They
Speaker 3: can and spend a lot of money to try to
Speaker 3: do the first demonstrations, but we'll have to shrink them
Speaker 3: and make the more cost effective all the components that
Speaker 3: go in.
Speaker 1: Eventually, it's like we did for any algorithm.
Speaker 3: Yeah, exactly, and that part will happen. It just requires
Speaker 3: you to start building these larger systems and for the
Speaker 3: companies that are making the individual components for them to
Speaker 3: have larger volumes so they can.
Speaker 2: Drive on costs.
Speaker 3: But where it's particularly challenging right now is actually in
Speaker 3: the control electronics. Like the costs about maybe ten thousand
Speaker 3: dollars a little more than ten.
Speaker 2: Thousand dollars just for the control used for every single fewbit.
Speaker 3: Wow, and we need to go to maybe a million
Speaker 3: few bits or something. So that's like ten billion dollars
Speaker 3: just in the control hardware right if we were.
Speaker 2: To scale out what we have today.
Speaker 3: So it's very costly to imagine doing that, so right now, yeah,
Speaker 3: but then we'll get better. We'll do custom silicon chips,
Speaker 3: where the costs are in the scale of the electronics
Speaker 3: is much more efficient, So we'll do what are called
Speaker 3: ASEX or custom circuits that'll drive down costs tremendously, but yeah,
Speaker 3: that that has to happen, but it just you know,
Speaker 3: it's not We're not quite there yet.
Speaker 1: So there you have it. You can build a quantum
Speaker 1: computer in your garage right now for about a million dollars,
Speaker 1: although for that money right now, you could only put
Speaker 1: about twenty cubits on it, which is about as sophisticated
Speaker 1: as an abocus, although this case would be a quantum ebicus. Right.
Speaker 1: The last thing we'll talk about is why quantum computers
Speaker 1: are so hard to make. If they can break any
Speaker 1: encryption on the planet, or potentially let us simulate new
Speaker 1: chemicals and materials, why haven't we done it? What is
Speaker 1: so hard about making a quantum computer? Here's Oscar explaining it.
Speaker 3: Probably the thing that makes it most difficult, and maybe
Speaker 3: it's the most relevant to talk about, is that let's
Speaker 3: say you want to do a computation with a quantum computer,
Speaker 3: and you want to describe it by a certain number
Speaker 3: of particles, and you want to use those particles to
Speaker 3: do your quantum simulation. Then you need to be able
Speaker 3: to control those particles right, to manipulate them to do
Speaker 3: the computation you want. But if those particles interact with
Speaker 3: the environment, then part of the information that you wanted
Speaker 3: to control or manipulate will actually evolve and become connected to.
Speaker 2: These other particles.
Speaker 3: And that's the really tricky problem is how do I
Speaker 3: control tiny little quantum particles with my grubby little hands,
Speaker 3: so to speak. So I have to be able to
Speaker 3: send in these control signals to and manipulate these quantum particles,
Speaker 3: but I can't let in any other parts of the
Speaker 3: environment in the same time, and so it becomes a
Speaker 3: really hard problem to sort of shield the system you're
Speaker 3: trying to use to do this computation, but then also
Speaker 3: allow yourself these control knobs.
Speaker 1: Is it like a question of purity to.
Speaker 3: Some degree, yes, Like the properties electron have to be
Speaker 3: just that electron, and they interact with other things that
Speaker 3: you're not able to control, you lose the information.
Speaker 2: All right.
Speaker 1: So the reason that quantum computers are so hard to
Speaker 1: make and run basically goes back to Schrodinger's cat. Might
Speaker 1: have heard of this analogy when people are talking about
Speaker 1: quantum things, And the idea is that if I take
Speaker 1: a cat and I put it inside a box, and
Speaker 1: I also put in the box a quantum particle that
Speaker 1: might kill the cat. Then when I close the box,
Speaker 1: eventually the cat becomes both alive and dead at the
Speaker 1: same time. And that's because when I close the box,
Speaker 1: the quantumness of that killer particle basically extends to the
Speaker 1: cat itself. Now, a quantum computer is basically like taking
Speaker 1: a whole bunch of those boxes with cats that are
Speaker 1: alive and dead at the same time, and it tries
Speaker 1: to do math with them. And because all those cats
Speaker 1: are in that magical quantum state of being two different
Speaker 1: things at the same time, alive and dead, then you
Speaker 1: can do some really powerful computations with them, like multiply
Speaker 1: a whole bunch of numbers all at the same time.
Speaker 1: But as soon as anyone takes a peek inside one
Speaker 1: of those boxes and the whole thing collapses. As soon
Speaker 1: as you open one box and you see whether the
Speaker 1: cat is alive or dead, then that box loses its
Speaker 1: quantum magic, and all the other boxes that are talking
Speaker 1: to it will also lose their quantum magic. So the
Speaker 1: reason you need to build giant refrigerators and keep these
Speaker 1: computers in an almost perfect vacuum with perfect coldness is
Speaker 1: to protect them from any random bit of motion or
Speaker 1: energy from essentially peeking inside your quantum boxes, because if
Speaker 1: that happens, the whole thing collapses and stops working. And
Speaker 1: this problem only gets worse as you make the computers
Speaker 1: bigger and more complicated. But people like Oscar are getting
Speaker 1: better and better at it. Well, that was great, that
Speaker 1: was awesome. I guess just the last question, what is
Speaker 1: the current state of the art in quantum computers?
Speaker 3: Yeah, so I think that if you can look at
Speaker 3: this on I would say three axis, so you can
Speaker 3: ask how many physical cubits can I make in.
Speaker 1: Control right now?
Speaker 2: Right?
Speaker 1: What's the highest number of somebody that has been So.
Speaker 3: If you just said I just want to be to
Speaker 3: control this many cubits, it's a few hundred. And people
Speaker 3: have made systems of more than a few thousand, but
Speaker 3: maybe not controlled all of them simultaneously. But people have
Speaker 3: definitely made a few hundred and controlled them. So we're
Speaker 3: getting to that level. And you might say, well, okay,
Speaker 3: put that in context, and if we could control them
Speaker 3: with high enough fidelity and not make errors, we would
Speaker 3: be at the point where we could actually start to
Speaker 3: access and solve problems of practical utility better than we
Speaker 3: think other computers can, like we could answer some of
Speaker 3: these questions about how electrons interacted materials, like small toy problems,
Speaker 3: but still useful.
Speaker 1: So like, if I have a thousand cubits working, yeah,
Speaker 1: what kinds of passwords can I break? Right now?
Speaker 2: Yeah?
Speaker 3: So, like the number of bits and an RSA key
Speaker 3: is like a few thousand, So if I had a
Speaker 3: few thousand cubits, I could crack RSA a.
Speaker 1: Few thousand, and we're at one thousand now. Yeah, so
Speaker 1: right now we can maybe crack simple passwords.
Speaker 3: Like yeah, surely that's right, shorter short of ones that
Speaker 3: we can already do classically, So probably not useful, but
Speaker 3: we're within striking. But the bigger problem is that we
Speaker 3: can't do those calculations because our calculations are too air prone.
Speaker 2: Then we need to add the air correction.
Speaker 1: Okay, that's the other that's the root axs.
Speaker 3: And that's adding redundancy, and so really think about it this.
Speaker 3: I need to not have just a few thousand physical cubits,
Speaker 3: but I may need a few million because the redundancy
Speaker 3: factor is pretty large right now, Like if my hardware
Speaker 3: had no errors, I wouldn't need to do any air
Speaker 3: correction and the redundancy factors one. But I do have errors,
Speaker 3: and the errors we have right now require about another
Speaker 3: factor of one thousand overhead a thousand cubits multiple thousands
Speaker 3: of times, so it'd be a thousand times of thousand,
Speaker 3: which is a million. If I need a thousand cubits
Speaker 3: to do computations with, I have to multiply that by
Speaker 3: one thousand, and that gives me how many physical cubits
Speaker 3: I need to represent?
Speaker 2: Oh wow, So.
Speaker 3: That's why I'm saying we probably needed like a million
Speaker 3: physical cubits. So that's what people are doing right now.
Speaker 3: The fact is that we can actually build and control
Speaker 3: on order a few hundred one thousand cubits is amazing, right,
Speaker 3: that's huge progress.
Speaker 1: Like ten years ago it was z there are cubits.
Speaker 3: I would say we became masters of the individual cubit
Speaker 3: so to speak. Maybe even in two thousand we're really
Speaker 3: really good at that. It was very hard to first
Speaker 3: even figure out, like to control a single cubit. But
Speaker 3: since then we've been already growing small cubit systems and
Speaker 3: improving how the interacting in the gates that we can implement.
Speaker 3: There was a recent result where scientists at Google showed
Speaker 3: that their processor would require ten twenty years for a
Speaker 3: classic computer to simulate what they've done the processor. You know,
Speaker 3: our own team hit Amazon. We focused on a slightly
Speaker 3: different hardware implementation that potentially has an ability to reduce
Speaker 3: the hardware overhead by factors on the order five to ten,
Speaker 3: which could be very important. So, even though it doesn't
Speaker 3: have a practical application yet, it's clear like there's a
Speaker 3: big difference in the power of what these things can do.
Speaker 3: There are a set of problems that the class computers
Speaker 3: are just not going to be good at, and there's
Speaker 3: going to be a set of things that quantic computers
Speaker 3: can do that classical ones cannot mimic. And if you're
Speaker 3: watching this as a sort of an interested techy observer
Speaker 3: and look looking for a turning point or a tipping point,
Speaker 3: I'd be watching for how these air rates go down,
Speaker 3: how efficient air correction is in these sort of one
Speaker 3: hundred two thousand cubit systems over the next few years.
Speaker 1: Very cool, Well, thank you so much, Oscar. That was fantastic.
Speaker 3: Yeah, I hope we got into enough of the detail
Speaker 3: where it's understandable enough. It is definitely a difficult subject
Speaker 3: and there's a lot of hype around it. Even for me,
Speaker 3: it's very hard to read the news and to decipher
Speaker 3: what is really an advance of what isn't. And I'm
Speaker 3: deep in the field, so I can only imagine for
Speaker 3: others that read about it.
Speaker 2: Very cool, right, all right?
Speaker 1: Thanks a lot, yep, and that is how a quantum
Speaker 1: computer works. Thanks for going on this field trip with me.
Speaker 1: I hope you enjoyed that. See you next time. You've
Speaker 1: been listening to Science Stuff. Production of iHeartRadio written and
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