Speaker 1: Brought to you by the reinvented two thousand twelve Camray.
Speaker 1: It's ready. Are you get in touch with technology with
Speaker 1: tech Stuff from how stuff works dot com. Hello everyone,
Speaker 1: welcome to tech Stuff. My name is Chris Poulette and
Speaker 1: I am an editor at how stuff works dot com.
Speaker 1: Sitting across from me, or maybe he's not, or maybe
Speaker 1: all of the above, the senior writer, Jonathan Strickland, Darling,
Speaker 1: you've got to let me know should I stay or
Speaker 1: should I go? Excellent? Thank you. So today we wanted
Speaker 1: to tackle an incredibly complex subject, which is a quantum computers.
Speaker 1: We've talked a little bit about quantum computers in previous podcasts,
Speaker 1: but we haven't really dedicated a full episode to it,
Speaker 1: and part of that is because it scares us. Yeah,
Speaker 1: and you'll probably see why as soon as we get
Speaker 1: further into the discussion today. Yeah. The the the potential
Speaker 1: for quantum computers is phenomenal. Yes, it potentially could be
Speaker 1: a true breakthrough in computing for certain applications. But the
Speaker 1: actually describing what a quantum computer does and how it
Speaker 1: works is a pretty herculean task for for the layman.
Speaker 1: And this is where Chris and I both say, neither
Speaker 1: of us are quantum physicists. We are not experts in
Speaker 1: quantum mechanics by any stretch of the imagination. Although I
Speaker 1: do know that they used to work on VW midsize
Speaker 1: sedans in the eighties. It wasn't mid sized sedans, it
Speaker 1: was quantum size sedans. Yeah, because it doesn't work on
Speaker 1: the classical system. Um, we're gonna get into that. Actually. See,
Speaker 1: to really understand how a quantum computer works, you have
Speaker 1: to know a little bit about quantum mechanics. And this
Speaker 1: is a crazy kind of world for those of us
Speaker 1: who are accustomed to things working on the classical level.
Speaker 1: So for to kind of ease into this. For me,
Speaker 1: physics was an easy class in general. I was able
Speaker 1: to grasp the concepts of physics pretty quickly. And the
Speaker 1: reason I uh I give to that is because I
Speaker 1: am a fairly observant person, and physics really was just
Speaker 1: a way of explaining why the things I see work
Speaker 1: the way they work. Yeah, I I didn't split off
Speaker 1: on that vector very easily myself. Um, you know, I
Speaker 1: think I think my interests in high school when I
Speaker 1: took physics were not where they where they would have
Speaker 1: been now, maybe I should go back through it. Well,
Speaker 1: physics though, ultimately, I mean once you get past the
Speaker 1: equations and the formulas, once you get past that, that barrier,
Speaker 1: that mathematical barrier that exists for some of us. I mean,
Speaker 1: I know there are math whizz is out there that
Speaker 1: they they see mathematics as a beautiful expression of the universe,
Speaker 1: which is phenomenal to me. It's just that doesn't come
Speaker 1: naturally to me. However, the concepts behind it made perfect
Speaker 1: sense to me because it described the world I live in. Right,
Speaker 1: So so I'm like, well, of course, you know, the
Speaker 1: deceleration from gravity makes sense because of this. I mean
Speaker 1: I I can observe that and and draw conclusions from
Speaker 1: and in fact, that's where physics comes from. It are
Speaker 1: these observations of the universe, trying to make uh, explanations
Speaker 1: for those observations, and predictions based on those observations, and
Speaker 1: testing that out over time to make sure that they
Speaker 1: are relevant and and accurate. Right, I mean, that's that
Speaker 1: was the basis of that science. Well, right, I mean
Speaker 1: it's easy for you to you know, shove a book
Speaker 1: off the table and watch it hit the floor and
Speaker 1: be able to explain that because that's something that you
Speaker 1: can see, but quantum mechanics is not something that you
Speaker 1: can see exactly. Quantum mechanics deals with elements that are
Speaker 1: on the atomic or subatomic scale, So we're talking about
Speaker 1: things that are so tiny that it is very difficult
Speaker 1: to observe them in any classical sense. You can, you
Speaker 1: can observe some quantum effects using a classical system, but
Speaker 1: there are complications that will get into in a second.
Speaker 1: But on the quantum level, things behave in a really weird,
Speaker 1: funky way. And we don't fully understand all of the
Speaker 1: the aspects of quantum mechanics. And when I say we,
Speaker 1: I'm talking about super yeah, super smart people who make
Speaker 1: it their livelihood to study and try to understand quantum mechanics.
Speaker 1: We know bits and pieces. We don't know if there
Speaker 1: is an overall system that everything fits neatly into place.
Speaker 1: We we hope there is, so that we can explain everything,
Speaker 1: but we can't know that yet. We just don't have.
Speaker 1: You know, it's kind of like you've been given, uh,
Speaker 1: five or six little tiny, tiny pieces of a puzzle
Speaker 1: and you can't really be sure that they're all belonging
Speaker 1: to the same picture. And you're trying to put the
Speaker 1: picture together just based on those little tiny pieces, right right, Well,
Speaker 1: and the analogy holds for classical computers. It's hard to
Speaker 1: think of computers as being classical, but in this sense
Speaker 1: classical computers versus quantum computers because um, when you talk
Speaker 1: about the computers that we use every day, laptops, desktops,
Speaker 1: other kinds of computers, we're talking about things that are
Speaker 1: fairly standard. Now. I mean, we use materials like, uh,
Speaker 1: silicon and mercury and lead and glass and all sorts
Speaker 1: of other things that we are pretty familiar with. We
Speaker 1: know how the properties work. Now we have the semiconductors
Speaker 1: and transistors. You know, these things are are pretty common.
Speaker 1: I mean can basically you know, computer science as far
Speaker 1: as the hardware and software goes. And this also does
Speaker 1: apply to programming. We'll get into that in a few minutes.
Speaker 1: But um, you know, the the things are fairly standard
Speaker 1: to the point where you know, the layman is pretty
Speaker 1: familiar with the guts of a computer. But quantum computers
Speaker 1: use materials that we don't use in classical computers at all.
Speaker 1: And not only that, but in a system that is
Speaker 1: really complex to the sense in the sense that you
Speaker 1: have to you have to isolate the computing elements from
Speaker 1: the overall system, because if you don't, the computer breaks down. Um.
Speaker 1: But to understand that, we need to talk about some
Speaker 1: of the the features of the quantum mechanics world. One
Speaker 1: of those is the wave particle duality concept, which is
Speaker 1: that certain elements, certain things behave as both a wave
Speaker 1: and a particle. And the classic experiment to demonstrate this
Speaker 1: is called the double slit experiment. Now, this is an
Speaker 1: experiment where you have a thin sheet of material and
Speaker 1: in that thin sheet of material you cut two vertical
Speaker 1: slits that are close together, all right, and then behind
Speaker 1: the thin sheet of material you've got a a wall,
Speaker 1: essentially a target. You start to fire particles at this
Speaker 1: sheet of material it has these two slits, and detect
Speaker 1: where they hit on the on the target. Now, if
Speaker 1: you were to shine light at this at this double
Speaker 1: slitted material, you would observe on the other side, uh,
Speaker 1: some some little bands of light where the lights passing
Speaker 1: through the slits, and the bands would have little dark
Speaker 1: sections between them or within them even which would show
Speaker 1: where the waves of light are interfering with one another.
Speaker 1: All right, So so you see the interference pattern from light,
Speaker 1: And that's because light behaves, at least in part like
Speaker 1: a wave. It can also behave as a particle, but
Speaker 1: we'll get into that. So that's the wave behavior of
Speaker 1: of light. You see that those inference patterns um. Now
Speaker 1: let's say instead of light, you're firing electrons at these
Speaker 1: double slits. Now, presumably you've got something on that wall
Speaker 1: that's going to detect where the electron hits. After as
Speaker 1: an individual shot of an electron going through those double slits,
Speaker 1: you'll just see that it appears on one specific spot,
Speaker 1: all right, So you're like, oh, well, here's where the
Speaker 1: electron landed. Uh. After you've done repeated shots of electrons
Speaker 1: through those double slits over and over and over again.
Speaker 1: The interesting thing is when you look at the accumulation
Speaker 1: of those spots, they're going to fall within that same
Speaker 1: sort of uh pattern as the light did when the
Speaker 1: wave forms were interfering with one another. So you're gonna
Speaker 1: see those dark bands appear, showing that somehow the electron
Speaker 1: is behaving both as a particle in a wave, meaning
Speaker 1: that every time you fire an electron at that double
Speaker 1: slit of material, the electron is somehow passing through each
Speaker 1: of those slits, because it's only if there's an interference
Speaker 1: that those bands are going to appear. Otherwise you wouldn't
Speaker 1: expect to see the bands, like the dark bands within
Speaker 1: the collision area. You wouldn't expect to see those appear
Speaker 1: at all. Otherwise it would just be a continuous line
Speaker 1: within wherever the double slits would allow the electron to hit.
Speaker 1: That means that somehow the electron is in two places
Speaker 1: at one time, and it's only you know, it's doing
Speaker 1: that while it's moving through, but by the time it hits,
Speaker 1: when you look at it, it's clear that it's it
Speaker 1: had to be in one space because there's only one
Speaker 1: impact point per electron. Now, this is insane to someone
Speaker 1: who's looking at this on the classical level. How how
Speaker 1: can something be in two places at the same time
Speaker 1: and yet ultimately be in one place at the end
Speaker 1: of it. That would be a good time to pause
Speaker 1: the podcast and take some headache reliever medicine. Yeah, because
Speaker 1: it's gonna get weirder from here on out, all right. So,
Speaker 1: there were people who had been there's some people who
Speaker 1: had some problems with this idea of of the wave
Speaker 1: particle duality. Of this this idea of not just that
Speaker 1: something can behave as both wave and a particle, but
Speaker 1: that it could somehow be in two places at one time.
Speaker 1: Einstein had some issues with this um and created some
Speaker 1: thought experiments. But there's an UH and and and then
Speaker 1: there were There's a related concept, at least related within
Speaker 1: quantum mechanics called entanglement, which is this is also pretty complex,
Speaker 1: but the ideas essentially is that let's say you've got
Speaker 1: a particle and it has a certain number of states
Speaker 1: it can exist in. In other words, there's some sort
Speaker 1: of feature or behavior this particle can have or not have,
Speaker 1: and that that one way of describing this particle. Now
Speaker 1: we'll go with electrons and say that this electron could
Speaker 1: have one of two different spins, so it could be
Speaker 1: spinning up or it could be spinning down. Now UH.
Speaker 1: Within quantum mechanics, another, yet another UH concept is called superposition.
Speaker 1: Superposition describes a system's ability to to occupy multiple states
Speaker 1: at one time, like there's no way to determine until
Speaker 1: you measure it which state it's in, So therefore it's
Speaker 1: in all of those states at the same time. And
Speaker 1: the best part is if you observe this, you will
Speaker 1: affect what's actually happening. Yes, it it goes through decoherence.
Speaker 1: It decoheres, which means that the quantum state collapses and
Speaker 1: it becomes a classic system, not a quantum system, at
Speaker 1: least to the observer, which means that, so you have
Speaker 1: this electron that could be either spinning up or spinning down.
Speaker 1: From a quantum level, we would say it's doing both
Speaker 1: at the same time, which is because it's a Superposition's
Speaker 1: a superposition right Mathematically, if we were to describe the system,
Speaker 1: we would have to say it's doing both because we
Speaker 1: cannot determine at this time which one it is um
Speaker 1: and it behaves as if it's doing both in multiple experiments.
Speaker 1: So entanglement means that you could have another particle interact
Speaker 1: with that first one, and then its behavior is dependent
Speaker 1: there or their behaviors are dependent upon each other. So
Speaker 1: in the classic sense of the electron spinning up, you
Speaker 1: might have a second electron that you introduce into this system,
Speaker 1: and it's always going to spin down if the other
Speaker 1: one spinning up, and vice versa. Now again, if you
Speaker 1: haven't measured it yet, you cannot be certain which what
Speaker 1: electrons are doing what So both electrons are acting in superposition.
Speaker 1: They're both spinning up and down. There, that's what they're doing.
Speaker 1: They're spinning up and down. And it's only when you
Speaker 1: measure one that you determine that that the system collapses
Speaker 1: and you see, all right, it's spinning up. Well, by
Speaker 1: knowing that that spent that electron is spinning up, you
Speaker 1: then know the other electron, which has entangled with the
Speaker 1: first one, is spinning down and you don't have to
Speaker 1: mess with it. You're want to measure it. If you
Speaker 1: do measure it, you realize it's spinning down. So you've
Speaker 1: already determined the measurement by measuring the first one. Uh.
Speaker 1: Now this Einstein also had a big problem with because
Speaker 1: entanglement is uh there are certain types of entanglement that
Speaker 1: are have non locality. So locality is talking about how
Speaker 1: close these things are to one another. If you have
Speaker 1: a system that where you've got entangled particles that are
Speaker 1: non local, it means that it doesn't matter how far
Speaker 1: apart those two particles are, they're going to behave this way,
Speaker 1: so that if you measure one, you know the other one.
Speaker 1: This in theory gives us the ability to communicate over
Speaker 1: huge distances. Um, if we're able to manipulate this in
Speaker 1: such a way so that uh, the information, like you know,
Speaker 1: the information that exists in another location, no matter how
Speaker 1: far away it is, Like even if it's on the
Speaker 1: other side of the universe, you instantly know the state
Speaker 1: of that particle. That means that you the information has
Speaker 1: traveled faster than the speed of light. That's the problem
Speaker 1: Einstein had, because nothing travels faster than the speed of light,
Speaker 1: except possibly information. So if I've got a system here
Speaker 1: on Earth, and there's another system across the universe, perhaps
Speaker 1: set to a Beatles tune, uh felt that one coming.
Speaker 1: I can, I can, and and my system is entangled
Speaker 1: with that system. By by observing and measuring my system,
Speaker 1: I now know the state of the other system across
Speaker 1: the universe without having to be there to measure it.
Speaker 1: And and this is again kind of crazy for anyone
Speaker 1: who's thinking up from a classical point of view, because
Speaker 1: it's that's just not the way stuff appears to work
Speaker 1: to us on the macro level. Now, I wish I
Speaker 1: had remembered my pain reliever medication. I do, However, I
Speaker 1: hope to avoid any imperial entanglements. Nice, thank you, thank
Speaker 1: you made the Kessel running twelve post sex. It's fast
Speaker 1: enough for you, old man. Um. So yeah, so quantum
Speaker 1: computers rely on this idea on on multiple ideas, superpositions
Speaker 1: and entanglement in particular, and uh and just another aside.
Speaker 1: I know we've done a lot of prep works here
Speaker 1: in the sides, but it's it is really important to
Speaker 1: kind of get that that information about quantum mechanics across um.
Speaker 1: You may have heard of a thought experiment called Schrodinger's cat,
Speaker 1: and Chris actually alluded to it earlier in the podcast.
Speaker 1: Schrodinger's Cat was and uh, well, Schroedinger was using this
Speaker 1: as a thought experiment to kind of show the absurdity
Speaker 1: of the quantum world compared to the classical world um.
Speaker 1: And it wasn't necessarily to ever state that such an
Speaker 1: experiment is should be carried out, but rather just that
Speaker 1: it shows how how how insane to us this world is.
Speaker 1: Troanjer's thought experiment is this. You've got a steel box.
Speaker 1: You put a cat in the steel box. The steel
Speaker 1: box also has a Geiger counter which has some nuclear material,
Speaker 1: some radioactive material in it. That's undergoing radioactive decay um
Speaker 1: and within an hour and atom of this material within
Speaker 1: the Geiger counter may or may not decay into another element.
Speaker 1: All right, so you've got you've got uh this this uh,
Speaker 1: this uncertainty here. You don't know whether or not that
Speaker 1: adam is going to decay within an hour. The guy
Speaker 1: your counter is hooked up to a system where if
Speaker 1: it detects that an adom has decayed, it will break
Speaker 1: some glass and some acid will be released into the box,
Speaker 1: which will kill the cat. You seal the box and
Speaker 1: you wait an hour, so you don't know if the
Speaker 1: atom has decayed within that hour. Now, based upon the
Speaker 1: the traditional interpretation of quantum mechanics and this idea of superposition,
Speaker 1: you would say that the cat before you open the
Speaker 1: box to observe it, is both alive and dead. It
Speaker 1: has to exist in both states at the same time.
Speaker 1: And only by opening the box and observing it will
Speaker 1: this quantum state collapse. It'll decohere and you will see
Speaker 1: definitively whether the cat is alive or dead. Now, there
Speaker 1: are a lot of philosophical objections to this. Not not
Speaker 1: I mean, it's all thought experiment anyway, right, It's not
Speaker 1: like people are actually gonna do this, but philosophical in
Speaker 1: the sense of, wait a minute, So from the cat's perspective,
Speaker 1: it's going to know whether or not it was dead. Well,
Speaker 1: if it's dead, it doesn't know anything. If it's alive,
Speaker 1: then it knows it didn't die. So the point being
Speaker 1: that how can you say it is both alive or
Speaker 1: dead because it's going to have no memory of such
Speaker 1: a being in such a state. Others have said that.
Speaker 1: Another objection is that, well, we talk about measuring a system,
Speaker 1: and that's what causes it to collapse. Some people would
Speaker 1: argue that it that opening up the box isn't necessary
Speaker 1: for that system to be measured. The Geiger counter inside
Speaker 1: the system is already a measuring device and is measuring
Speaker 1: part of that system, and just by measuring part of
Speaker 1: the system, it deco hears and becomes a classical system,
Speaker 1: so that the cat, the cat's life or death is
Speaker 1: not It's never a superposition thing in the first place.
Speaker 1: But this is one of those thought experiments that is
Speaker 1: meant to kind of make people think about this and
Speaker 1: try and figure out, all, right, well, how do we
Speaker 1: resolve this problem of our description of how the universe
Speaker 1: works and we don't have all the answers yet. There
Speaker 1: are a lot of different interpretations two quantum mechanics, and
Speaker 1: they some of them are fairly contradictory to one another.
Speaker 1: And you've got adherence to multiple different approaches and we
Speaker 1: don't have the full solution yet. This finally brings us
Speaker 1: to quantum computers. So here's another crazy thing about innovation.
Speaker 1: Sometimes we find out that something really cool happens when
Speaker 1: we do a certain action and we don't really know
Speaker 1: the mechanism behind it, but we go ahead and build
Speaker 1: stuff anyway. Yeah, a lot of sometimes great things happen
Speaker 1: because of this. Sometimes bombs happen because of this. But
Speaker 1: quantum computers almost fits into that realm because we don't have,
Speaker 1: like I said, a full understanding of quantum mechanics. But
Speaker 1: the idea behind the quantum computer is that you create
Speaker 1: some sort of system that uses sub atomic particles that
Speaker 1: have a particular feature, Like I was talking with the
Speaker 1: electron spin. That could be an example. It's not the
Speaker 1: only one, but it is an example of this. And
Speaker 1: you know that because of superposition, the electrons spin is
Speaker 1: all every every type of spin that it can be. Well,
Speaker 1: if you translate this into the classical computer system, which
Speaker 1: relies on bits. And if you've listened to our Logic
Speaker 1: Gates episode, we talked a lot about this. There are
Speaker 1: two states a bit can be in orffe yeah, or
Speaker 1: one or zero. Yes, exactly, because you said on or off,
Speaker 1: I was going to confuse everybody. Yes, or true or false.
Speaker 1: That would be the other way of looking at it, right.
Speaker 1: It can't be both true and false, right, right, So yeah,
Speaker 1: an individual bit is either going to be true or false,
Speaker 1: one or zero, on or off in a classical classical computer. Now,
Speaker 1: quantum computers use something called cubits. They're also great for
Speaker 1: measuring an arc. Actually, cub i t. The cub it
Speaker 1: in a quantum bit is a qub it, which is
Speaker 1: a little orange guy who hops up and down pyramids.
Speaker 1: Uh no, wait, that's cue Bert. So cube bit is
Speaker 1: a is is the fundamental element of information within a
Speaker 1: quantum computer system, and unlike a regular classical computer bit,
Speaker 1: a cubit is able to be a zero or a one,
Speaker 1: or any value of zero or one or all of them,
Speaker 1: or all of the values of zero or one. Yeah,
Speaker 1: that's not confusing. It exists in superposition, and so if
Speaker 1: you have two cubits together, then you've got all the
Speaker 1: different combinations of zero and one that two bits would have.
Speaker 1: H three cubits, you've got all the different combinations of
Speaker 1: zero and one that three bits would have. So exponentially
Speaker 1: it becomes a more powerful computer for certain computing problems.
Speaker 1: Haircut two. Yeah. So you you keep on adding more
Speaker 1: and more cubits, You've just created an incredibly powerful theoretical computer.
Speaker 1: And there have been some some advances in creating computers
Speaker 1: that use cubit technology. Uh, although we still have a
Speaker 1: lot of ground to cover in order to really make
Speaker 1: one that is um, that is practical. Yes, as a
Speaker 1: matter of fact, you listed some of those I believe
Speaker 1: that I I might have there. Well, there is a
Speaker 1: list in the article how quantum computers work on the website.
Speaker 1: Kevin Vonsa and I both worked on this article, and
Speaker 1: it's yeah, it's there have been several the first being
Speaker 1: back in where am I t researchers and Lost Alamos
Speaker 1: researchers were able to create a single cube it across
Speaker 1: three nuclear spins in a molecule of or in in molecules,
Speaker 1: I should say, of a liquid solution of of alanine,
Speaker 1: which is an amino acid. Yeah, this is what I
Speaker 1: was talking about before. We're not using the traditional materials,
Speaker 1: the silicon and metals that we use to manipulate information
Speaker 1: in a classical computer. This this kind of computer is
Speaker 1: going to require a brand new style of physical architecture. Yes,
Speaker 1: And remember when I mentioned about superposition and entanglement and decoherents.
Speaker 1: That's the reason why you have to be able to
Speaker 1: isolate the actual computing element from the system it's end,
Speaker 1: because if it comes into contact with the system, it's
Speaker 1: and you you have that problem of decoherens and quantum collapse,
Speaker 1: or you have a problem of entanglement where the system
Speaker 1: is getting entangled with the actual environment it's in and
Speaker 1: it's no longer able to do what you needed to do. Uh.
Speaker 1: These are real problems and it's it's there's no easy
Speaker 1: way to describe the solution to it. And there are
Speaker 1: a lot of different approaches that that scientists are are
Speaker 1: taking to try and create quantum computers, including a creating
Speaker 1: quantum computers that operate at a temperature close to absolute zero, yes,
Speaker 1: which is very very cold absolute zero by the way,
Speaker 1: In case you do not know that is the point
Speaker 1: where you have no molecular movement whatsoever. Uh, And even
Speaker 1: deep space usually be is a few uh kelvin over
Speaker 1: absolute zero because it's it's not easy to create a
Speaker 1: system where every single molecule in that system is is
Speaker 1: completely motionless. Yeah, that's that's one of the troubles here
Speaker 1: is that this is not something that's easy to achieve,
Speaker 1: no or cheap. It's really expensive that too. So what
Speaker 1: kind of problems could a quantum computer solve. Let's say
Speaker 1: that we've created a quantum computer and it exists with
Speaker 1: these cubits that can have any sort of value of zero, one,
Speaker 1: or all of those values all at the same time.
Speaker 1: What would you use that for? Well, you wouldn't use
Speaker 1: it to play doom. No. One of the advantages of
Speaker 1: quantum computers is that the superposition of the cubits would theoretically,
Speaker 1: assuming that you know, we get to the point where
Speaker 1: we can have a fully operational um. Yes, uh, fully
Speaker 1: operational quantum computer. You you could theoretically. Now we talked
Speaker 1: about parallel processors before, we're talking infinite parallelism um, which
Speaker 1: means that you could crunch a massive amount of data
Speaker 1: and no time flat The thing is. You're right, you
Speaker 1: could use it for something like do but that would
Speaker 1: be like trying to cut open a grape with a chainsaw. Oh,
Speaker 1: you might as well just use a regular computer, because
Speaker 1: it's not gonna do that. It's not gonna it's not
Speaker 1: good for doing um, simple computing problems. It's not gonna
Speaker 1: do those any faster than a classical computer. Not really.
Speaker 1: It's it's meant for doing very specific types of computer problems.
Speaker 1: For example, factoring large prime numbers, which is the basis
Speaker 1: of a lot of cryptography out there. Not all cryptography,
Speaker 1: but a lot of it. So when you encrypt files, uh,
Speaker 1: one of the methods of encryption involves taking a large
Speaker 1: prime number. And when I say large, I'm talking hundreds
Speaker 1: of digits long. All right. You take this incredibly long
Speaker 1: prime number. Then you take another prime number of approximately
Speaker 1: the same number of digits, but a different one. So
Speaker 1: you've got two different, really really really large prime numbers.
Speaker 1: You multiply the two together. You get a product. Yes,
Speaker 1: you give that product to someone else. If they have
Speaker 1: one of those two large prime numbers, they've got the
Speaker 1: key to figuring out the other large prime number. And
Speaker 1: then you can use that to encrypt information. But if
Speaker 1: they do not have the key, if they do not
Speaker 1: have one of those two large prime numbers, they have
Speaker 1: to figure out, all right, what two prime numbers were
Speaker 1: multiplied to create this product. And when you're talking about
Speaker 1: a number that large, breaking that down, breaking that encryption
Speaker 1: can take years or centuries with a classical computer, because
Speaker 1: the classical computer what's going to do is it's going
Speaker 1: to start finding the factors for that particular product, and
Speaker 1: then it has to determine which ones are prime numbers
Speaker 1: and which ones arn't. So I might start with, all right,
Speaker 1: is it divisible why two? Yes? So is the other
Speaker 1: number a prime number? No? Alright? Is it divisible by three? Yes?
Speaker 1: All right? Is the other number of prime number? No?
Speaker 1: All right? Is a divisible wy four? Weight? That doesn't
Speaker 1: matter because four is not a prime number. So I
Speaker 1: mean no, no, it would have to figure That's what
Speaker 1: the classical computer would have to do. It goes bit
Speaker 1: by bit by bit. Now I was just imagining the
Speaker 1: computer argument. No are you idiots? I thought I had it,
Speaker 1: and then it turns out four is not a prime number.
Speaker 1: Oh sorry, I see these things in my I see
Speaker 1: this in my head. Yeah, anyway. Yeah, so yeah, has
Speaker 1: to go through the entire series. Right, And and if
Speaker 1: you're talking about parallel program or parallel computing, Uh, if
Speaker 1: you have a computer that has a multi core processor, well,
Speaker 1: each core of that processor may be able to work
Speaker 1: on a part of a problem similar to this and
Speaker 1: thus solve it in less time. But when we're talking
Speaker 1: about these large prime numbers in this encryption technique, even
Speaker 1: a multi core processor would take centuries to solve it.
Speaker 1: It's not it's not fast enough to really reduce that
Speaker 1: time to a practical limit. Yeah, a lot of our
Speaker 1: our computers today use quad core processes, and that's great
Speaker 1: for doing all kinds of everyday stuff, but working on
Speaker 1: a problem of that magnitude just doesn't and it would
Speaker 1: take a well, it's still gonna take a long time.
Speaker 1: We're gonna get to I'm sure eight and sixteen core processors,
Speaker 1: but still, and even if you create a grid computing
Speaker 1: network where you have uh, you are you are leveraging
Speaker 1: the processing power of multiple computers, each computer with multiple processors,
Speaker 1: Even then it's taking it's gonna take ages to solve
Speaker 1: this problem. But using a quantum computer with enough cubits
Speaker 1: where where it has enough cubits for all the different inputs. UM.
Speaker 1: It can then run this sort of problem where since
Speaker 1: all the cupids are are in superposition uh and it
Speaker 1: can run all all the different potential solutions in parallel
Speaker 1: and come back with a solution in seconds where it
Speaker 1: might take centuries for a classical computer system. UH. There
Speaker 1: are a few problems with this, the first being that
Speaker 1: UM as soon as you observe the system, you have
Speaker 1: broken down that it decoheres and you and it becomes
Speaker 1: a classical computer. So you just turned your quantum computer
Speaker 1: into a classical computer and this is not reversible. Oops.
Speaker 1: Also the other problem being that the solutions that a
Speaker 1: quantum computer represents are given in terms of probability, not
Speaker 1: in terms of certainty. So in other words, you're going
Speaker 1: to receive a series of solutions and you'll essentially know
Speaker 1: which one it has the most probability of being the
Speaker 1: correct solution, but it may take multiple calculations to UH
Speaker 1: two make that probability feel like that like that's the
Speaker 1: answer you want to go with UM And and even so,
Speaker 1: there's still some problems that a quantum computer just may
Speaker 1: or may not be good at solving and there's added
Speaker 1: complexity here. If you remember back to our logic Gates
Speaker 1: episode just a few weeks ago, we were talking about
Speaker 1: certain how how logic can classical computers flows in a
Speaker 1: certain direction, and there are some logical operations that cannot
Speaker 1: be reversed. Here here's here's part of the problem. In
Speaker 1: quantum computers, all operations have to be reversed. I mean
Speaker 1: they have to be reversible. So some of the logical
Speaker 1: operations used in classical computing just don't operate the same
Speaker 1: way with quantum logic. And in addition to this, the
Speaker 1: superposition of the cubits also requires a different style of programming.
Speaker 1: You have to be able to write programs in a
Speaker 1: completely different way quantum algorithms using quantum algorithms, and that
Speaker 1: means again you can't play doom on it. So which
Speaker 1: is still is a huge bummer to be big doom
Speaker 1: fans well know that. But if you if you back
Speaker 1: off of this, we're looking at the big picture here
Speaker 1: and not you know, the quantum picture quantum computers since
Speaker 1: since they use such a different way of computing and
Speaker 1: it's a different physical architecture, it's a different intellectual architecture
Speaker 1: and programming. That means you have to completely reinvent the
Speaker 1: way you compute, and it's not an inexpensive way to
Speaker 1: re engineer the computer either. So although people are building
Speaker 1: quantum computers, it is unlikely that we're going to see
Speaker 1: them on our desktops and our laptops. It's not even
Speaker 1: It may even be years before we see one that
Speaker 1: is truly capable of of doing the things that we
Speaker 1: suspect quantum computers are capable of doing. Um and and
Speaker 1: the kinds of problems that quantum computers can tackle are
Speaker 1: generally called b q P problems, which stands for bounded
Speaker 1: error quantum polynomial time problems. Yeah uh, and so they
Speaker 1: that's those are the ones that those are the type
Speaker 1: of problems that quantum computers we think would be ideal
Speaker 1: for solving. But of course not all problems fall into
Speaker 1: that category. There's another kind of problem that may or
Speaker 1: may not be at all connected to b q P
Speaker 1: problems called MP complete problems. And I'm not gonna get
Speaker 1: into too much detail here because we're gonna have to
Speaker 1: really dive into complex computer science in order to explain it.
Speaker 1: But um, but in general, there some people have proposed
Speaker 1: that quantum computers could possibly solve NP complete problems. And
Speaker 1: there are other people who completely disagree and say, no,
Speaker 1: MP complete problems fall outside the realm of what a
Speaker 1: quantum computer could could attack. I'll just give you an
Speaker 1: example of an MP complete problem. And again this is
Speaker 1: just an example, not a This isn't like the end
Speaker 1: all be all, Okay, it's uh. This is called this
Speaker 1: is an MP hard problem. Uh, the traveling salesman problem. Mhmm.
Speaker 1: Have you heard about this one. I've had a problem
Speaker 1: with some traveling salesman before. Well, this is a little
Speaker 1: bit different than that, the so that you've heard about that.
Speaker 1: I guess everybody read about that in the paper. You
Speaker 1: know you eventually you're gonna if you listen hard enough.
Speaker 1: I just don't tamper with my ankle bracelet, and everything's okay. Now,
Speaker 1: Really I should say that the this is an MP
Speaker 1: hard problem, uh, not necessarily an MP complete problem, because
Speaker 1: I want to say that before we have all our
Speaker 1: math mathematicians right in, but I wanna you know, again,
Speaker 1: this is one of those things where we know a lot,
Speaker 1: but we don't know all the intricacies, all the connections
Speaker 1: between these types of math problems to be able to
Speaker 1: say definitively what is and is not solvable by a
Speaker 1: quantum computer. But it's a The traveling salesman problem is
Speaker 1: a sort of an optimization problem. Right. So we say
Speaker 1: that you are a traveling salesman. You have a list
Speaker 1: of cities that you need to visit on your route
Speaker 1: to to make sales. And it's your job to try
Speaker 1: and determine the fastest or the shortest route to take
Speaker 1: where you don't uh retrace your steps at all among
Speaker 1: the those cities. And then every time you add another
Speaker 1: city to that list, you have just made the problem
Speaker 1: much more complex. And it's determining, all right, well, there
Speaker 1: are in number of possible routes for me to take,
Speaker 1: and only one of them is going to result in
Speaker 1: the shortest distance between two spaces. But then you add
Speaker 1: another city, all right, well, now it's in plus one,
Speaker 1: in plus two, and in in plus three. And that's the
Speaker 1: sort of problem that could maybe be solved by a
Speaker 1: quantum computer. It's it's hard to determine. I mean, it's
Speaker 1: again whether or not it falls into that realm of
Speaker 1: b QP. But that's sort of the that's an example
Speaker 1: of a problem that may not be solvable by quantum computers.
Speaker 1: We've seen quantum computers actually tackle problems like Pseudoku puzzles.
Speaker 1: So there are some, uh of these sort of parallel
Speaker 1: problems that we know quantum computers could tackle. We just
Speaker 1: don't know the full extent of it. It's complicated, man. Well,
Speaker 1: it is interesting to think that they have they have
Speaker 1: been able to build some quantum computers, even to the
Speaker 1: point where they're they're operating on a que bite which
Speaker 1: is eight que bits um. You know, I'm I'm fascinated
Speaker 1: by this, but it is pretty amazing stuff. I mean,
Speaker 1: it's it's really not simple even for maybe even probably
Speaker 1: because I am so immersed in the world of classical computing,
Speaker 1: you know, I've done programming and some of the immersed
Speaker 1: in the classical world period. Yeah, yeah, and I think
Speaker 1: of it's hard for me to imagine something existing in
Speaker 1: more than one state at the same time. So, um, here,
Speaker 1: I I was gonna say, in doing my story, say
Speaker 1: and doing my research, I read an article called an
Speaker 1: Introduction to Quantum Computing for non Physicists by Eleanor Reefal
Speaker 1: and wolf GETG. Pollock. Um I beg to differ with
Speaker 1: the non physicist part, but it still was it still
Speaker 1: was a good read, and they broke down a lot
Speaker 1: of things, but they really got into it, and I
Speaker 1: would uh suggest that if you're really interested in reading that.
Speaker 1: In addition to the article on how stuff works dot com,
Speaker 1: how quantum computers work, and we have other interesting quantum
Speaker 1: articles on the site, the big one being the one
Speaker 1: that the one that's a favorite of our general manager
Speaker 1: is quantum suicide. Yeah. Yeah, I don't know how many
Speaker 1: times has Connell mentioned quantum suicide. I don't know, but
Speaker 1: it's well, it's a favorite of a lot of our
Speaker 1: fans too. It's indicative, it's indicative of a deeper psychological issue,
Speaker 1: I think. And that concludes this final episode text stuff.
Speaker 1: I don't know this, Connell, so listen, hey conal uh So, anyway, guys,
Speaker 1: that wraps up our discussion of quantum computers and again
Speaker 1: the applications for this maybe a complete revolution of how
Speaker 1: we do cryptography. For example, because if quantum computers are
Speaker 1: capable of breaking down those those um those large factor numbers,
Speaker 1: then clearly that would no longer be a safe way
Speaker 1: to encrypt information. And again, it's not the only way
Speaker 1: to encrypt information, but it would just mean that we'd
Speaker 1: have to move away from that and adopt something else
Speaker 1: that quantum computers might not be so good at doing
Speaker 1: um calling missnomials polynomial nice and on that theorem. We
Speaker 1: are going to conclude this episode. If you guys want
Speaker 1: us to tackle a subject, maybe something that's you know,
Speaker 1: less fuzzy and scary and spooky, or Einstein would call
Speaker 1: it spooky. He called it spooky action. That was the
Speaker 1: whole entanglement thing. Um. Einstein was pretty awesome. Yeah, If
Speaker 1: you guys want us to tackle a similar subject, or
Speaker 1: there's just something totally different you think that we should
Speaker 1: talk about, let us know. Drop us an email. Our
Speaker 1: address is text stuff at how stuff Works dot com,
Speaker 1: or let us know on Facebook or Twitter that handle
Speaker 1: there is Text Stuff h s W. Chris and I
Speaker 1: will talk to you again really soon. Be sure to
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