Speaker 1: Hey, please take a second and leave us a review
Speaker 1: on Apple Podcasts, Spotify, or wherever you listen to the podcast.
Speaker 1: Thanks a lot, Hey, Happy New year. In case you
Speaker 1: didn't know, twenty twenty five was the Year of Quantum,
Speaker 1: the year where we celebrated the one hundredth anniversary of
Speaker 1: the development the theory of quantum mechanics. So to end
Speaker 1: the year, we're going to re air our episode that
Speaker 1: answers the question what is a quantum computer. It's a
Speaker 1: good episode because it's a nice introduction to quantum ideas
Speaker 1: and you'll hear what it's like to go inside an
Speaker 1: actual quantum computer lab. We'll be back next week with
Speaker 1: a new episode about the science of imagination, What is
Speaker 1: it and how does it work in your brain? So
Speaker 1: be sure to come back next week for that, But
Speaker 1: until then, please enjoy this field trip into the quantum world. Hey,
Speaker 1: welcome to Sigence Stuff, a production of iHeartRadio. My name
Speaker 1: is hoorheitch Ham and to the end of the program, we
Speaker 1: are talking about a technology that made potentially impact the
Speaker 1: life of every single human on Earth and might change
Speaker 1: how we protect data and come up with passwords. It
Speaker 1: might help us make new and exciting materials, and it
Speaker 1: might render cryptocurrencies like Bitcoin and dotgecoin totally useless. I'm
Speaker 1: talking about quantum computers. What are they, how do they work?
Speaker 1: And most exciting is that we're going to get to
Speaker 1: visit one of them and actually hear it in action.
Speaker 1: So power up your curiosity, log in, and let's answer
Speaker 1: 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. We're going to talk about
Speaker 1: how they're made and why they're so hard to get
Speaker 1: them to work. Our guide through all of this is
Speaker 1: 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. A. Hey,
Speaker 1: os Care, how.
Speaker 2: Are you good to see you 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 2: Yeah, it's been a while. Happy to try to fill
Speaker 2: you in on some of the things we've been doing
Speaker 2: 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.
Speaker 2: Now.
Speaker 1: The word quantum is the word we used to describe
Speaker 1: how things behave at the level of atoms and the
Speaker 1: tiny little particles that make up the atoms. So in
Speaker 1: our everyday lives, we're used to things being solid and
Speaker 1: us being able to hold them. Like, for example, if
Speaker 1: you take a piece of wood or a ball. But
Speaker 1: if you take that piece of wood or ball and
Speaker 1: you chop it up, and you keep chopping it up,
Speaker 1: you get down to atoms, and then you'll notice that
Speaker 1: those atoms don't behave in the same way that a
Speaker 1: piece of wood or a ball do. Here's how Oscar
Speaker 1: explains it.
Speaker 2: It turns out that down to the microscopic scale, so
Speaker 2: not our everyday scale of things, the laws of physics
Speaker 2: that dominate in that regime is quantum mechanics, and quantum
Speaker 2: mechanics is our theory that has some strange attributes that
Speaker 2: we don't experience every day. Exact ample, it postulates that
Speaker 2: things can be in superposition, so you can have objects
Speaker 2: being in sort of what we think of as two
Speaker 2: distinct realities at the same time. Imagine having a particle
Speaker 2: in one position and another position simultaneously. That seems very
Speaker 2: 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 2: Right, it's sitting there 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 2: You would find that if you repeated the measurement or
Speaker 2: finding its position multiple times, you might find that, Oh,
Speaker 2: I get this weird outcome that sometimes I measure it here,
Speaker 2: sometimes I measure it there. And that's because it's actually
Speaker 2: in many places at once, all right, And that's fundamental
Speaker 2: to the description of quantum mechanics. The way I like
Speaker 2: to think about quantum mechanics is really as waves and amplitudes.
Speaker 2: So think about you're at a pond and you throw
Speaker 2: a rock in a pond, and you see this ripple
Speaker 2: of the rock. Right, That's how I think about, Like
Speaker 2: the rocks are sort of the particles, and these wave
Speaker 2: phenomena are sort of the actual physical quantum mechanical description
Speaker 2: 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. Yeah, that's right,
Speaker 1: it's this wave.
Speaker 2: So I may have started with something that was very local,
Speaker 2: like that rock, but then it becomes very quickly it
Speaker 2: sort of propagates out and is actually better described as
Speaker 2: this wave on the pond, because.
Speaker 1: Like a ripple and a wave in a pond like that,
Speaker 1: it's kind of in a lot of places at the
Speaker 1: same exactly.
Speaker 2: That's right. And then the interference is important to understand.
Speaker 2: If I throw two rocks in the pond, then I
Speaker 2: see the sort of interference of the ripple patterns coming
Speaker 2: from each rock that flashed 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 2: 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 2: Classical computers are formed from things that are very very
Speaker 2: classical in nature.
Speaker 1: And they operate kind of on hard switches.
Speaker 2: Yeah, like, yeah, that's right. The transistors on your phone
Speaker 2: what we call these types of elements. The transistors are
Speaker 2: used to store information or perform calculations, and the transistors
Speaker 2: are really set by a bunch of electrons in part
Speaker 2: of the circuit. And usually you're talking about quite a
Speaker 2: few electrons.
Speaker 1: Because regular transistors are huge. They're bigger than an atom.
Speaker 2: Yes, exactly, that's physically what's going on in your phone.
Speaker 2: And what I'm telling you is that the way to
Speaker 2: think about it is in the quantum case, I just
Speaker 2: have one electron.
Speaker 1: Like, the circuits are made out of individual electrons.
Speaker 2: Yeah, atoms is exactly what you're doing or a quantum
Speaker 2: particle doesn't have to be electrons, can be other particles.
Speaker 2: That was the sort of very early idea from people
Speaker 2: like FIM and others back in the nineteen eighties is
Speaker 2: if you're going to do this, and you better make
Speaker 2: 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 bit 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 2: Classic computers are formed from digital bits and they go
Speaker 2: between one and zero. A quantum computer doesn't have these
Speaker 2: hard zero one states. It has every possibility in between.
Speaker 2: So imagine if we have these two states zero in one.
Speaker 2: I told you that a quantum system can be in
Speaker 2: two different states at once, right, So it can be
Speaker 2: in zero and one at the same time, and I
Speaker 2: can have a different weight of zero or one at
Speaker 2: the same time. It could be ten percent zero ninety
Speaker 2: percent one.
Speaker 1: It's like a shade of gray.
Speaker 2: Yeah, And so you have all those possibilities in between.
Speaker 2: It can be zero or one or anything in between.
Speaker 1: It can be black, white, dark, gray, light gray exactly.
Speaker 2: So it has all those shades in between. You can
Speaker 2: take zero with some fraction and add it to one
Speaker 2: with any other fraction. You can have any combination of that.
Speaker 1: So an 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 a 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 it lets you do math with it. Now,
Speaker 1: actually it's not doing all of those multiplications or calculations
Speaker 1: at the same time. It's more like how Oscar described
Speaker 1: it earlier. If you drop two rocks in a pond,
Speaker 1: you see the two ripples spread out and mix together
Speaker 1: to form a complex ripple pattern. That's more of the
Speaker 1: picture of what a quantum computer does. It doesn't do
Speaker 1: calculations with hard numbers. It does calculations with the ripples
Speaker 1: and patterns of quantum numbers. Of course, my next question
Speaker 1: for Oscar was what is that good for? Why would
Speaker 1: you want to do math? This way? When we come back,
Speaker 1: I'm going to ask Oscar what quantum computers are for,
Speaker 1: and then at the end we're going to go check
Speaker 1: out the ones he's built. You're listening to science stuff.
Speaker 1: Welcome back. Okay, to recap, we learned that a quantum
Speaker 1: computer is a regular computer whose circuits are made with
Speaker 1: individual atoms or small particles like electrons, and by doing
Speaker 1: that you can do quantum calculations. That is, you can
Speaker 1: do math, but with numbers that are actually lots of
Speaker 1: different numbers at the same time. So now the question
Speaker 1: is why would you want to do that? What are
Speaker 1: quantum computers? Four? Here's more of my conversation with quantum
Speaker 1: physicists Oscar Painter. Let's say it's a few years into
Speaker 1: the future and we have quantum computers, yes, in our phones,
Speaker 1: like I have one in my pocket, what can I
Speaker 1: do with it? And how is my life different?
Speaker 2: I think that's a very unlikely scenario. Okay, I think
Speaker 2: that's the wrong way to think about how quantic computers
Speaker 2: might change our lives, at least as far as I
Speaker 2: can project into the future. I think the best way
Speaker 2: to think about a quantic computer as we envision it
Speaker 2: right now is that it will be more like a supercomputer.
Speaker 2: So a supercomputer is just a very large computer that
Speaker 2: can perform calculations beyond what our desktop, our personal computers
Speaker 2: can do. And these are usually very large, almost building
Speaker 2: scale computers and computer clusters that have many, many different
Speaker 2: processing units that are all integrated together, and through that
Speaker 2: scale you can perform a huge number of computations per
Speaker 2: second and therefore compute some of the hardest problems that
Speaker 2: are out there. A lot of them are used for
Speaker 2: chemistry problems. They're used to study particle physics, so fundamental physics,
Speaker 2: trying to understand models of quantum particles that are beyond
Speaker 2: the current standard model. There used to compute the properties
Speaker 2: of materials, climate modeling, and things like that.
Speaker 1: So usually science and tech, yeahs, and.
Speaker 2: There's always this competition between different nations who has the
Speaker 2: 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 2: It's going to be some very special type of supercomputer
Speaker 2: that can solve specific problems that quantic computers will be
Speaker 2: very effective at that we can't do today on classic computers,
Speaker 2: no matter how much we scale them up. And the
Speaker 2: key is, it's not just a faster supercomputer. It performs
Speaker 2: calculations in a fundamentally different way, and therefore it can
Speaker 2: tackle problems that are possibly outside of the reach of
Speaker 2: these conventional classical supercomputers. What do you mean, out of
Speaker 2: the reach meaning that no matter how fast they get
Speaker 2: or how big they get, they'll never be able to
Speaker 2: compute some.
Speaker 1: Of these problems, never or take an infinite Yeah, exactly.
Speaker 2: It's just the scaling is so bad for these problems.
Speaker 2: You would take way too long and require way too
Speaker 2: large on machine. So no matter how hard we work
Speaker 2: on our current computing technology, it has limits, and it's
Speaker 2: known and you can prove it for certain problems. And
Speaker 2: quantic computers when they looked at theoretically these same problems,
Speaker 2: they realize that the same restrictions or limitations for quantum
Speaker 2: computers are not there. There's examples where we believe and
Speaker 2: strongly believe that certain mathematical problems that are important are
Speaker 2: really really hard to perform and can't be solved using
Speaker 2: classical means, no matter how 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 to, say, just fill
Speaker 1: the world with them.
Speaker 2: You still won't be able to do it. Yet a
Speaker 2: quantic computer can solve it pretty efficiently.
Speaker 1: Well, step me through some of these problems.
Speaker 2: Like so the example that everyone points to, and it
Speaker 2: is pretty amazing that people found this, But there's this
Speaker 2: mathematical problem and it just happens to be very applicable
Speaker 2: to our safety or security of our data. So it
Speaker 2: turns out that most of the security of all of
Speaker 2: the data you hold, all the data that banks or
Speaker 2: various institutions around the world want to be safe and protected,
Speaker 2: they typically encrypt it. And those encryption techniques that have
Speaker 2: been used were what are called RSA encryption, where you
Speaker 2: want to take a large number and understand what its
Speaker 2: 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 2: So I give you a number, and I say, tell
Speaker 2: me what the prime factors are, and you have to
Speaker 2: break it down to its prime factors. So you know,
Speaker 2: a simple one is, you know, like two, it's just
Speaker 2: one times two, one and two those are the two
Speaker 2: prime factors, right, But it gets harder as these numbers
Speaker 2: get bigger.
Speaker 1: If I tell you one million, three hundred forty three.
Speaker 2: Yeah, thirteen, very hard to actually answer what those what
Speaker 2: the prime factors are. But if I give you the
Speaker 2: prime factors, you can multiply them together and very quickly
Speaker 2: get the answer to what that larger number is.
Speaker 1: Right.
Speaker 2: And so if you know the prime factors, I can
Speaker 2: give you what they multiply to. But if you give
Speaker 2: me the number that they multiply to without then I
Speaker 2: have a very hard time finding out what the prime factors.
Speaker 1: Are because you'd have to get you kind of have
Speaker 1: to guess.
Speaker 2: Well, you know, there's mathematical techniques to try to find these,
Speaker 2: but they're very inefficient. And so it turns out that
Speaker 2: most of the security of the way we encrypt information
Speaker 2: is based upon that asymmetry and how hard the problem is.
Speaker 1: So now, let's say somebody has a quantum computer.
Speaker 2: Right, then they can find those prime factors and they
Speaker 2: can now decrypt all that information.
Speaker 1: They can just grab it from the air, yeah and
Speaker 1: be like, oh, I.
Speaker 2: Know, yeah, I can find the prime factors and then
Speaker 2: I can use that to decrypt the information.
Speaker 1: That would be easy for a quantum computer you just
Speaker 1: press a button and will tell you, Oh, this is
Speaker 1: an oscar or his secret decoder.
Speaker 2: Yeah exactly, so that would you know. That obviously concerned
Speaker 2: 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: au 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 2: Another example is maybe more natural to think about, and
Speaker 2: this is where quantum computers were first proposed. It to
Speaker 2: be interesting or useful, and that is the simulation of
Speaker 2: nature itself. Nature as we know it is not classical.
Speaker 2: If you peel the layers of the onion enough and
Speaker 2: you get down to the core, right to the atomic scale,
Speaker 2: it turns out that the laws of physics that dominate
Speaker 2: is quantum mechanics. Okay, like the actual mathematics of that
Speaker 2: When you describe it. When you have many particles, it
Speaker 2: quickly becomes something that you can't simulate with a classical computer.
Speaker 2: So all those interference of all the particles and keeping
Speaker 2: track of all of that. A classical computer, if you
Speaker 2: try to simulate that, you quickly run out of steam
Speaker 2: and it becomes an exponentially hard problem. And so you know,
Speaker 2: a classical computer is just ill suited to doing that.
Speaker 2: But a quantum computer that's made out of the say
Speaker 2: those sort of particles that can do with that interference naturally,
Speaker 2: you know, has a natural advantage in terms of using
Speaker 2: it to simulate the natural world at its quantum mechanical core.
Speaker 1: Why would I want to do that?
Speaker 2: Yeah, so that's the questions like, okay, so that's great,
Speaker 2: But why would I want to do that other than
Speaker 2: maybe I want to understand physics better. Well, this idea
Speaker 2: that I want to understand how material behaves is a
Speaker 2: very good example. If I'm building an electrical circuit, or
Speaker 2: I'm building a new battery, or I'm building a different
Speaker 2: energy process inside of a material or energy storage device,
Speaker 2: A lot of times that depends on what the electrons
Speaker 2: are doing. If I want to understand is there something
Speaker 2: unique when I describe them quantum mechanically. Maybe there's special
Speaker 2: properties I'm just totally blind to. So if I wanted
Speaker 2: to make a better superconnecting material, something that can carry
Speaker 2: a electricity with no resistance, right, maybe we can have
Speaker 2: magnetically livitated trains. Maybe you can have you know, really
Speaker 2: efficient electrical circuits that don't dissipate any energy. All of
Speaker 2: these things. Then I would have to use a quantic
Speaker 2: computer to model that behavior.
Speaker 1: And you said there's some maybe potential applications in chemistry
Speaker 1: and biology.
Speaker 2: Yeah, you know, if I think about what is going
Speaker 2: on when I have a chemical reaction, usually it comes
Speaker 2: down to the electrons, and I need to understand what
Speaker 2: they're doing in order to understand, you know, whether this
Speaker 2: chemical reaction is going to be efficient or not, or
Speaker 2: if I want to describe it with chemical accuracy so
Speaker 2: I can use it to, you know, do some sort
Speaker 2: of industrial chemical process. The biological application, it's like, if
Speaker 2: I want to know how molecules are biologically relevant molecules
Speaker 2: lined together, then potentially I need to know more information
Speaker 2: about the electronic behavior in these molecules. If I wanted
Speaker 2: to do that without having approximation or with much higher accuracy.
Speaker 2: Then a quantic computer would be potentially more capable.
Speaker 1: There we might be able to predict better how a
Speaker 1: vaccine will work, or whether a certain chemical into this
Speaker 1: in your body will.
Speaker 2: Right now, we don't have that sort of level of specificity.
Speaker 2: I mean, we'd love too. People are proposing techniques, but
Speaker 2: that's the right idea, by the devil's in the details.
Speaker 2: And you know, you have people saying, well, look, you know,
Speaker 2: I think even today there's I won't call them skeptics,
Speaker 2: but there's a lot of people that are saying, well,
Speaker 2: I can keep improving my classical algorithms, and whether you
Speaker 2: can really gain advantage from the quantum simulations is as
Speaker 2: a practical question. And maybe we don't have as clear
Speaker 2: an example or as clear a win when it comes
Speaker 2: to how quantum computers will will do better or be
Speaker 2: more efficient, or be able to do the calculations fast
Speaker 2: or even do them ones that the classical computers can't do.
Speaker 2: But I think there's definitely something there. It's just that
Speaker 2: we still have to work on the quantum algorithms. It's
Speaker 2: not as clear cut I would say.
Speaker 1: So those are the two main applications or uses for
Speaker 1: quantum computers. One is in breaking encryption using a special
Speaker 1: algorithm called face 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 out 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. Well, not in my.
Speaker 2: Basement, but in my my laboratory. Yeah here, can we
Speaker 2: go see it? We can?
Speaker 1: Okay, yeah, let's get see it.
Speaker 2: Okay, you want to do that now?
Speaker 1: Okay, so where are we going?
Speaker 2: Just the next door. We don't actually even have to
Speaker 2: go down into the basement, into the basement, No, we
Speaker 2: can the basement.
Speaker 1: Sounding is more yeahd scientists exactly.
Speaker 2: So let's so all these labs have different variants of
Speaker 2: quantic computers that we're testing. Multiple quantum computers here, yeah, yeah,
Speaker 2: not just one. So there's small scale quantum computers, but
Speaker 2: the largest ones are you know, ones at Amazon or
Speaker 2: Google or IBM or you know some of the other
Speaker 2: startup companies. These get to be maybe a factor of
Speaker 2: ten times larger than the ones I'll show you. Okay, okay,
Speaker 2: so this gives you an idea all of these control electronics,
Speaker 2: right is to use to an about twenty of these
Speaker 2: quantum bits.
Speaker 1: There's twenty quantum twenty particle made up of twenty quantum
Speaker 1: particles correct.
Speaker 2: Right, which we are manipulating as quantum bits, and that
Speaker 2: circuit lies 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 2: And this refrigerator is under vacuum, under high vacuum. It's
Speaker 2: a temperature which is about ten million degrees above apsoute zero.
Speaker 1: Ten million degrees.
Speaker 2: So to give you an idea, so if I go
Speaker 2: to the deepest part of space, it's a few degrees calvin,
Speaker 2: a few degrees about that food and zero the coldest
Speaker 2: darkest parts of outer space or that universe. But this
Speaker 2: thing's about thirty times colder than that.
Speaker 1: Even WHOA, So would you say that some of the
Speaker 1: coldest places in the whole universe?
Speaker 2: I mean no, I mean you can get and there's
Speaker 2: people that do this for a living that make really
Speaker 2: cold things. 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 2: Because even the lights, even if we turned all the
Speaker 2: lights off, even just the fact that the room's hot.
Speaker 2: It's room temperature, but it radiates radiation, and that radiation
Speaker 2: would completely destroy the information in the corner.
Speaker 1: Bit I see. So we have to get it really dark.
Speaker 2: We have to make sure that there's not any of
Speaker 2: this thermal energy that's making it into the circuit, otherwise
Speaker 2: it'll destroy the manipulation of those count particles. And so
Speaker 2: it has to be as isolated as we can from
Speaker 2: the environment. We would ideally seal it off from everything,
Speaker 2: so it would be like zero temperature and there would
Speaker 2: be nothing coming in other than what we want to
Speaker 2: send to it to control it. And then you can
Speaker 2: see there's all of these cables.
Speaker 1: Each of these feeds.
Speaker 2: Into a microwave cable that can be used to control
Speaker 2: individual 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: with a quantum computer. Well, what's in there? So describeting
Speaker 1: what's inside the core of it? Is it like a
Speaker 1: little chip? Yeah?
Speaker 2: Like we shit, Okay, it's what's called a superconnecting quantum circuit.
Speaker 2: So it uses little metal traces on a silicon wafer
Speaker 2: that we pattern on the surface, and when you get
Speaker 2: them cold enough, they become superconnecting, which means they can
Speaker 2: carry electrical currents without any energy dissipation. Okay, And it
Speaker 2: turns out that you can form these sort of quantum
Speaker 2: particles like these atoms where the current is circulating in
Speaker 2: a clockwise way inside of a little tiny ring, or
Speaker 2: it's circulating counterclockwise, and the clockwise could be zero when
Speaker 2: the counterclockwise could be one, And you can get in
Speaker 2: any superposition of these two circulation patterns, and I can
Speaker 2: use that, and I can manipulate what the superposition is,
Speaker 2: and I can have an interact with other circulating currents
Speaker 2: to these little circuits things in our circuit. There are
Speaker 2: a few hundred microns in size, so they might be
Speaker 2: a few times the human hair diameter, so they're pretty
Speaker 2: big relative to conventional transistors. It's made out of many atoms,
Speaker 2: but it behaves like a single atom. Okay, yeah, theod
Speaker 2: way to think about it. So there's like a little
Speaker 2: array of these things, a little array of these things
Speaker 2: on the surface of a microchip, and then each of
Speaker 2: them we can control the current flow. So what are
Speaker 2: called single cubic gates. We bring them together and then
Speaker 2: let them interact them bring them apart. So I need
Speaker 2: to build to manipulate the single particle, put it in
Speaker 2: any sort of superposition I want. And then you have
Speaker 2: to read out the state of these cubits too. You
Speaker 2: have to know after I do my computation, are you
Speaker 2: in state zero or state one? All right, I have
Speaker 2: to ask that question for all my cubits and that
Speaker 2: will give me the answer I see hearing.
Speaker 1: So this is called the pulse tube cooler.
Speaker 2: Some oder sounds like if you were ever a kid
Speaker 2: growing up in the eighties and you watch Battlestar Galactica,
Speaker 2: there were the cylons and Battlestar Galactica.
Speaker 1: They walk and they would.
Speaker 2: Have this flashing light and they'd have this sort of
Speaker 2: sound coming from them. This is a similar sort of sound.
Speaker 2: This is a pulse tube cooler and is shooting a
Speaker 2: slug of helium gas onto a cold plate, and then
Speaker 2: in doing so, when it expands, it can cause cooling.
Speaker 2: It's analogous to what you do with the regular refrigerator.
Speaker 2: That's the first stage of cooling, though that only gets
Speaker 2: you down to maybe a tenth of the temperature of
Speaker 2: the room. And then if I want to go even
Speaker 2: cooler down and by another factor of ten or one hundred,
Speaker 2: then you have to use a recirculating gas. In this case,
Speaker 2: it's a dilution fridge that takes mixtures of isotopes of
Speaker 2: helium helium three and helium four, and when they mix
Speaker 2: there's an entapley of reaction and that's what gets you
Speaker 2: 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 2: There's actually like sort of three or four stages.
Speaker 1: If you're inside of a fridge, you have because of
Speaker 1: the fridge, the.
Speaker 2: One fridge is too hot for the other fridge, so
Speaker 2: we have to isolate them, and then we have to
Speaker 2: 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. Yeah, okay, exactly,
Speaker 1: I keep doing that.
Speaker 2: I add, you know another.
Speaker 1: Way, the fridge inside of my fridge have a restaurant freezer.
Speaker 2: And I keep you know, each of them has the
Speaker 2: ability to get colder and colder.
Speaker 1: Yeah, so you have to do it in stages.
Speaker 2: Otherwise, if you try to do a direct shot, it's
Speaker 2: too much of a thermal 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 is all the machinery needed to
Speaker 1: keep the actual circuit in the 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: there is definitely much bigger than my phone. Yes, exactly.
Speaker 2: That's why I was saying, you're probably not going to
Speaker 2: 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.
Speaker 2: Garage Okay, Well, you know there's always a big difference
Speaker 2: between science money and money that you know, when you're
Speaker 2: talking about conservative products that have large volumes. I remember
Speaker 2: the first time we purchased a big piece of equipment
Speaker 2: from my lab, when I was the first to saculty member.
Speaker 2: It was a bolt the same It was about smaller
Speaker 2: than this thing, so smaller than a few cubic feet,
Speaker 2: but it was more expensive than my.
Speaker 1: House when I bought it. So there's a big difference.
Speaker 2: But so just keep that in mind. But one of
Speaker 2: these systems today, because it's very specialized, probably costs about
Speaker 2: a million.
Speaker 1: Dollars to set up.
Speaker 2: Wow, that's another reason why you will probably won't carry
Speaker 2: it around in your pocket any times soon. But it's
Speaker 2: an important actually point to make, is that people will
Speaker 2: build these systems and go to the larger scales. I
Speaker 2: can and spend a lot of money to try to
Speaker 2: do the first demonstrations, but we'll have to shrink them
Speaker 2: and make the more cost effective all the components that
Speaker 2: go in.
Speaker 1: Eventually, it's like we did for any algorithm.
Speaker 2: Yeah, exactly, and that part will happen. It just requires
Speaker 2: you to start building these larger systems and for you know,
Speaker 2: the companies that are making the individual components for them
Speaker 2: to have larger volumes so they can drive down costs.
Speaker 2: But where it's particularly challenging right now is actually in
Speaker 2: the control electronics. Like the costs about maybe ten thousand
Speaker 2: dollars a little more than ten thousand dollars just for
Speaker 2: the control used for every single fubit. Wow, and we
Speaker 2: need to go to maybe a million fubits or something.
Speaker 2: So that's like ten billion dollars just in the control
Speaker 2: hardware right if we were to scale out what we
Speaker 2: have today, So it's very costly to imagine doing that,
Speaker 2: so right now, yeah, but then we'll get better. We'll
Speaker 2: do custom silicon chips, where the costs are in the
Speaker 2: scale of the control electronics is much more efficient, so
Speaker 2: we'll do what are called ASEX or custom circuits that'll
Speaker 2: drive down costs tremendously. But yeah, that that has to happen,
Speaker 2: but it just you know, it's not we're not quite
Speaker 2: 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 abacus, 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 2: Probably the thing that makes it most difficult, and maybe
Speaker 2: it's the most relevant to talk about, is that let's
Speaker 2: say you want to do a computation with a quantum computer,
Speaker 2: and you want to describe it by a certain number
Speaker 2: of particles, and you want to use those particles to
Speaker 2: do your quantum simulation. Then you need to be able
Speaker 2: to control those particles, to manipulate them to do the
Speaker 2: computation you want. But if those particles interact with the environment,
Speaker 2: then part of the information that you wanted to control
Speaker 2: or manipulate will actually evolve and become connected to these
Speaker 2: other particles. And that's the really tricky problem is how
Speaker 2: do I control tiny little quantum particles with my grubby
Speaker 2: little hands, so to speak. So I have to be
Speaker 2: able to send in these control signals to midp and
Speaker 2: manipulate these quantum particles. But I can't let in any
Speaker 2: other parts of the environment at the same time, and
Speaker 2: so it becomes a really hard problem to sort of
Speaker 2: shield the system you're trying to use to do this computation,
Speaker 2: but then also allow yourself these control knobs.
Speaker 1: Is it like a question of purity to some.
Speaker 2: Degree, yes, Like the properties electron have to be just
Speaker 2: that electron, and they interact with other things that you're
Speaker 2: not able to control, you lose the information, 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've
Speaker 1: heard of this analogy when people are talking about quantum things,
Speaker 1: and the idea is that if I take a cat
Speaker 1: and I put it inside a box, and I also
Speaker 1: put in the box a quantum particle that might kill
Speaker 1: the cat, then when I close the box, eventually the
Speaker 1: cat becomes both alive and dead at the same time.
Speaker 1: And that's because when I close the box, the quantumness
Speaker 1: of that killer particle basically extends to the cat itself. Now,
Speaker 1: a quantum computer is basically like taking a whole bunch
Speaker 1: of those boxes with cats that are alive and dead
Speaker 1: at the same time, and it tries to do math
Speaker 1: with them. And because all those cats are in that
Speaker 1: magical quantum state of being two different things at the
Speaker 1: same time, alive and dead, then you can do some
Speaker 1: really powerful computations with them, like multiply a whole bunch
Speaker 1: of numbers all at the same time. But as soon
Speaker 1: as anyone takes a peek inside one of those boxes,
Speaker 1: then the whole thing collapses. As soon as you open
Speaker 1: one box and you see whether the cat is alive
Speaker 1: or dead, then that box loses its quantum magic, and
Speaker 1: all the other boxes is that are talking to it
Speaker 1: will also lose their quantum magic. So the reason you
Speaker 1: need to build giant refrigerators and keep these computers in
Speaker 1: an almost perfect vacuum with perfect coldness is to protect
Speaker 1: them from any random bit of motion or energy from
Speaker 1: essentially peeking inside your quantum boxes, because if that happens,
Speaker 1: the whole thing collapses and stops working. And this problem
Speaker 1: only gets worse as you make the computers bigger and
Speaker 1: more complicated. But people like Oscar are getting better and
Speaker 1: better at it. Well, that was great, That was awesome.
Speaker 1: I guess just the last question, what is the current
Speaker 1: state of the art in quantum computers?
Speaker 2: Yeah, so I think that if you can look at
Speaker 2: this song, I would say three axis, So you can
Speaker 2: ask how many physical cubits can I make in control
Speaker 2: right now? Right?
Speaker 1: What's the highest number somebody has been.
Speaker 2: So if you just said I just want to be
Speaker 2: able to control this many cubits, it's a few hundred.
Speaker 2: And people have made systems of more than a few thousand,
Speaker 2: but maybe not controlled all of them simultaneously. But people
Speaker 2: have definitely made a few hundred and controlled them. So
Speaker 2: we're getting to that level. And you might say, well, okay,
Speaker 2: put that in context, and if we could control them
Speaker 2: with high enough fidelity and not make errors, we would
Speaker 2: be at the point where we could actually start to
Speaker 2: access and solve problems of practical utility better than we
Speaker 2: think other computers can. Like we could answer some of
Speaker 2: these questions about how electrons interacted materials, like small toy problems,
Speaker 2: 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? Yeah?
Speaker 2: So, like the number of bits and an rsa key
Speaker 2: is like a few thousand, So if I had a
Speaker 2: few thousand cubits, I could crack RSA.
Speaker 1: A few thousand, and we're at one thousand now. Yeah,
Speaker 1: so right now we could maybe crack simple passwords.
Speaker 2: Like yeah, that's right, short short ones that we can
Speaker 2: already do classically, so probably not useful, but we're within
Speaker 2: striking distance. But the bigger problem is that we can't
Speaker 2: do those calculations because our calculations are too air prone.
Speaker 2: Then we need to add the air correction. Okay, that's
Speaker 2: the other that's the and that's adding redundancy. And so
Speaker 2: really think about this. I need to not have just
Speaker 2: a few thousand physical cubits, but I might need a
Speaker 2: few million, because the redundancy factor is pretty large right now.
Speaker 2: Like if my hardware had no errors, I wouldn't need
Speaker 2: to do any air correction, and there's redundancy factors one.
Speaker 2: But I do have errors, and the errors we have
Speaker 2: right now require about another factor of thousand overhead. A
Speaker 2: thousand cubits multiply thousands of times, so it would be
Speaker 2: a thousand tuns of thousand, which is a million. If
Speaker 2: I need a thousand cubits do computations with I have
Speaker 2: to multiply that by one thousand, and that gives me
Speaker 2: how many physical cubits I need to represent? Oh wow,
Speaker 2: So that's why I'm saying we probably needed like a
Speaker 2: million physical cubits. So that's what people are doing right now.
Speaker 2: The fact is that we can actually build and control
Speaker 2: on order a few hundred one thousand cubits is amazing, right,
Speaker 2: that's huge progress.
Speaker 1: Like ten years ago it was zero cubits.
Speaker 2: I would say we became masters of the individual cubit
Speaker 2: so to speak. Maybe even in two thousand, we're really
Speaker 2: really good at that. It was very hard to first
Speaker 2: even figure like to control a single cubit. But since
Speaker 2: then we've been already growing small cubit systems and improving
Speaker 2: how the interacting in the gates that we can implement.
Speaker 2: There is a recent result where scientists at Google showed
Speaker 2: that their processor would require ten out twenty years for
Speaker 2: a classic computer to simulate what they've done their processor.
Speaker 2: You know, our own team Amazon, we focused on a
Speaker 2: slightly different hardware implementation that potentially has an ability to
Speaker 2: reduce the hardware overhead by factors on the order five
Speaker 2: to ten, which could be very important. So even though
Speaker 2: it doesn't have a practical application. Yet it's clear like
Speaker 2: there's a big difference in the power of what these
Speaker 2: things can do. There are a set of problems that
Speaker 2: the classic computers are just not going to be good at,
Speaker 2: and there's going to be a set of things that
Speaker 2: quantic computers can do that classical ones cannot mimic. And
Speaker 2: if you're watching this as a sort of an interested
Speaker 2: techy observer and looking for a turning point or a
Speaker 2: tipping point, I'd be watching for how these air rates
Speaker 2: go down, how efficient air correction is in these sort
Speaker 2: of one hundred two thousand cubit systems over the next
Speaker 2: few years.
Speaker 1: Very cool, Well, thank you so much, Oscar. That was fantastic.
Speaker 2: Yeah, I hope we got into enough of the detail
Speaker 2: where it's understandable enough. It is definitely a difficult subject,
Speaker 2: and there's a lot of hype around it. Even for me,
Speaker 2: it's very hard to read the news and to decipher
Speaker 2: what is really in advance of what isn't. And I'm
Speaker 2: deep in the field, so I can only imagine for
Speaker 2: others that read about it.
Speaker 1: Very cool, right, all right, thanks a lot, yep, And
Speaker 1: that is how a quantum computer works. Thanks for going
Speaker 1: on this field trip. With me. I hope you enjoyed that.
Speaker 1: See you next time. You've been listening to Science Stuff
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Speaker 1: executive producer Jerry Rowland, an audio engineer and mixer Casey Pegram,
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