 Welcome to this lecture today on nanotechnology. I'd like to thank the Institute of Physics for inviting me to talk to you today about something which is very close to my heart, which is my research. I'm a quantum physicist. I don't have a British accent, I'm actually Australian. And I'm working at the University of York in the very, very exciting area of nanotechnology. And I don't know if you realize it today, but do they tell you that you're all enrolled in my nanotechnology course today? No? Well, what we're going to try to do is I'm going to try to give you a little bit of the understanding of what goes behind the nanotechnologies, a little bit about the very exciting world of quantum physics, and then we're going to try to build some nanotechnology right here in the Faraday Lecture Theatre. Sound good? Woohoo! OK. Let's... We can only try. Let's see how far we go. So before we get started, what I'd like you to do is... I need to set the scene for this. I'd like you all to pluck a hair out of your head. And if you can't pluck the hair out of your head, pluck the hair out of somebody who's sitting next to you or in front of you. I'm serious about this. Next to you would be fine. And have a look at this hair. I seriously have a look at this hair, OK? Because all the technology that I'm going to be talking to you about, all of the technology on the nanoscale is within the width of a single hair. Now, how do we do the engineering of these technologies on such a small scale? And that's what this talk's going to be about. So what I'd like to do for you is to play you a little bit of a video to get you in the mood for the nanotechnology. N is for nanotechnology. The study of things less than one one thousandth the width of a human hair. These are the building blocks of nature and they can be rearranged to build some amazing things like a light bulb that never burns out or a car that can think or a cell phone so small an ant could use it or a shirt that can give you directions or a tiny computer that can hold every book ever written or maybe some things we haven't even thought of yet. All in less than the width of a human hair. N is for nanotechnology and it's brought to you by HP, a leader in this science of almost limitless possibilities. Brought to you by the Department of Physics at the University of York and the IOP. But that's just to give you a flavour of what this nanotechnology is all about. It's about quantum physics because when we get down to the scale of the atoms which is where we're really trying to do the engineering for nanotechnology we need to apply the quantum physics in order to come up with all these fantastic new devices that you have. But this is where we actually started. Can you believe it? This was the world's first computer. It was called the ENIAC and you can see its dimensions there. It's absolutely enormous taking up wall space and it was used for very simple arithmetic calculations and we've come a long way since then to this. I mean who doesn't love technology? And technology is getting smaller and smaller. This apparently is the world's smallest optical mouse. You can see the size of it relative to the human hand. This is actually a concept phone which I will show you a little bit about in a video a little bit later. And it's a phone which I'm actually involved in helping to research and to design. This is a Nokia phone. This is an iPod. Who's got an iPod? Who's got iPhones? The hands up. Who loves them? I mean I absolutely love technology. Really this video that we saw where you can get the mobile phone so small that an ant could use it. That's what I want to design basically. So this phone that I was telling about I want to play for you another video which will explain to you just how wonderful this new technology is. And I will talk over it so I can give you some explanation of it as well. Basically this device is extremely thin. And this is the future in terms of our technology. She's able to open it up. You can literally see through this device. It is amazing. So think of your iPad but think of something a million times better than that. She's wearing it on her wrist. So you can open it up and you can fold it. And this is a very new type of technology. It's called flexible electronics. Touch screens. The device is incredible. Multimedia does everything. And this is what I was telling you about. This is the new technology. The so-called stretchable electronics. And you'll see that there was a bit of material system which was bending. And this is called a graphene which is a single atomic layer of carbon atoms. And you can be very proud in the UK. In 2010 the Nobel Prize was awarded to two physicists at Manchester University for their work on this amazing material called graphene. And because it's so thin, it will open up the door to all of this amazing technology. Oh you can even buy your groceries with it. And of course if you want you can watch a movie as well. What actually can't it do? Now who wants one of those? I do. Yeah, okay. So we're in the process of trying to make this technology. Another type of technology that I'd like to introduce at this point here because we're getting, as I said, right down to this nano scale. And our controllability of these nano technologies is amazing. So I want to introduce a type of technology called a quantum dot which is literally a group of atoms, a very very small number of atoms together. And this group of atoms here you can see depending upon the size of this little cluster it will flourish at different colours. Okay now this is an important bit of technology which we can use for making sophisticated new devices. This here is the solid state version of it. This is a quantum dot in a little region of a semiconductor. Is this little space here. And inside that little space there are electrons. And we can tune the energy levels that the electrons have available to them. And in effect what we can actually do is get away with, throw away the periodic table and we can design our very own artificial atoms. So I want to give you a bit of a taste about that now. But we're going to talk also about the physics which makes this possible. So again welcome to my course, Nanotech 101. And we're going to talk a little bit about the quantum physics which is the physics behind these technologies. It's the physics down to the very very small scales, the world of the atoms basically. And just to give you some idea again about how small it is I know we had a look at the width of our human hair and all the technology is within the width of the human hair. But this is another way we can actually appreciate this scale. So if we have the earth here and we have a football, the ratio between the diameter of the earth and the diameter of the football would be the same as the ratio between the diameter of the football and the diameter of a nano object, the so-called bucky ball, which incidentally is made up of carbon atoms. So this is incredible if you think about these scales and trying to engineer on that level. How do we actually go about doing that? Well again we need to have some understanding of the world of the atoms and we need to have understanding of the quantum physics which is driving this world of the atoms. And the quantum world is probabilistic. Okay, so this is a challenge in terms of our engineering of the technologies on the scale. We're dealing with a world which is run on probabilities. So how do we actually work with that? In fact you can see a very famous physicist here, Professor Einstein. He didn't actually like the consequence of quantum physics in that the very small world of the atoms, how can this be possibly run on probabilities? He felt very uncomfortable about that. And he said very famously that God does not play dice. Well actually he does and this is the reality of what we have to deal with when we're designing nanotechnologies on these very small scales. The other thing that we need to have an appreciation for is what's driving the technology. So all the technologies that you have, the most important character, call it character that we need to deal with on the nanoscale to get you those technologies that you so love is the electron which is a negatively charged particle and one of the fundamental particles in the atom. And another property of the electron that we need to understand to build the technologies is what's called a spin, which is its intrinsic angular momentum. And you can think about this in terms of a bar magnet. And there are two types of spin and we have either spin up or spin down. So you can imagine your bar magnet is orientated one way or the other and that gives two flavours of these spins. And all the world of the atoms and the electrons and our understanding of it all goes together in the design process and the quantum physics on top of that. And these electrons are very, very sensitive to their environment. And when we're doing the engineering, we need to have a very good understanding of how these electrons basically think, you know, what they like to do, what they don't like to do. How can we control their atomic environment to get them to give us the technologies and the designs that we're trying to create? So it's a very complex thing, but we get a little bit of information from the quantum side. So in terms of understanding these electrons, how they relate to their environment is extremely important. So if you have a material system which is made up of, you know, positively charged ions, then the electron which is negatively charged is going to feel that. And because electrons are negatively charged themselves, they will also respond to each other. And in quantum physics, we say that an electron who looks like this is well-dressed. And this is an actual term that we use in quantum physics to describe an electron which feels its environment quite a lot. And if it's not feeling its environment, it's actually looking like this, which is an undressed particle. And of course these electrons, as I said, they're negatively charged and they respond to each other and they do something like this as well on the nanoscale. And this is what's called correlation. So they will move together and all of this understanding is essential if we're going to design new technologies which need the electrons to give us, you know, new nanoscale devices. So if we go back to some of the quantum theory concepts that we have, we go back to this important physicist, a de Broglie. And one of the conjectures that he came up with was this concept of quantum physics called wave particle duality. And so he explained this in 1924 and he was a young physicist at the time. In fact, this was part of his PhD work and after this, he was actually awarded a Nobel Prize. So that's something to aspire to. It's pretty amazing feat for a PhD student. So his proposal was that electrons could behave as waves. And again, this goes into trying to get to the root of our understanding of the nanotechnologies and understanding of the fundamental particle which drives them, namely the electrons. So we can have this link between the wave properties and the particle-like properties which is what de Broglie told us was a fact. And on the macroscopic scale, I mean, this is the thing about the quantum theory, is that we don't actually see evidence of it on our scale. It's only when you get down to these very, very small systems on the atomic scale that these effects become quite pronounced. And just to give you an example of that, if we were to calculate the de Broglie wavelength of a ping pong ball, for example, so we can use this equation here and we can work out that its wavelength is extremely small. So this is to give you evidence that objects on our scale, we don't have to worry about quantum effects, but when things get down to the atomic scale, we do. And in fact, the wavelength for an electron can actually be quite significant with the order of nanometres. And so if electrons have wave-like properties, does it go the other way? Do waves also have particle-like properties? And yes, there is experimental evidence of that. This is Young's Doubleslit experiment. So light of a wavelength, which is of the same order as the slit width here, will give a very nice diffraction pattern, but you can think of, well, what would happen if we had not light, but if we had electrons and electrons were going through two slits here? So we can heat up this little filament and we can eject electrons from it and we can conjecture what would happen. Well, classically, what you think would happen is that an electron would go through either this slit or this slit and you would get this effect building up on your screen. But what was shown by two physicists at Bell Labs, Davidson and Germa, was that what you actually get, if you do that experiment with electrons, is you get a wave-like phenomena. You get the diffraction pattern coming up. And similarly for light. Light is comprised of particles, a fundamental particle being the photon, and Albert Einstein in 1905 conjectured the theory, the so-called photoelectric effect, in which he put forward the idea that light was actually made of particles. And so we have this experimental evidence going both ways. And again, I cannot emphasise, this is a very important property to understand when we're having a look at the technologies. So I want to go back to this. If electrons can behave like waves, then what we could do is we could come up with a rudimentary model for an atom. And that rudimentary model would be this box here. And we could confine our electrons into this box. And so you can imagine that each one of these waves here, which are standing waves in this box, actually represent an electron. An electron in the lowest energy level, the first excited state, and the second excited state. And if you remember the image that I gave you earlier about the quantum dots, you will see that this was also there. So it's important in terms of our creation of the nanotechnologies. And this is driven by a wave equation invented by Schrodinger. But for nanotechnologies and size effects and understanding how size also matters, we can get a very good appreciation from this very simple model of an atom. So if I was to say that the energy is related to this equation here, what is important to understand in terms of the nanotechnology is that there is a size dependence on whether we get atom-like features or something in between, or whether we get something that we can pick up on the ground and have a look at with our own eyes. And so in this example here, if we have a much bigger box, then the distance between these quantised states becomes less. And we move away from this quantum picture to something else. And nanotechnology sits in this scheme here. So basically what we've learnt is that we have quantum effects on the nanoscale, that we need to have a very good understanding of the electrons which is driving the nanotechnology, that we have this wave particle duality that we can play with in terms of our nano-designs, and we have size effects as well. So to give you some appreciation of these size effects, if I have a single lithium atom, then these are the electronic energy levels available for it. As I start to put these atoms together, you can see that these energy levels, they become more of the energy levels, and also the other features that the energy levels become a lot closer together. So this is exactly what I was showing you with the box. And we get to a point where we have a solid and these distinct separations between these energy levels don't really exist anymore. And on the nanoscale, we're looking at this region here. So something which is not strictly an atom, is something which is not strictly a macroscopic solid, and something which can, in fact, be engineered and is very sensitive to what we do to it on these very small scales. And that's just a little bit of a summary in terms of Nanotech 101. But what we're really excited about, I suppose, is the applications of this. And yes, this is definitely a reality in what we have to deal with in being researchers in this field. So we're down to this very small scale design problem. And the question that you might have after learning a little bit more about the quantum side of it and having a look at the hair on your head and realizing that we really do need to be working at that small scale is, in fact, how do we actually design on that level? Well, in order to be able to do that, we need eyes to be able to see down on this nanoscale. And we use very special instruments, one of which is pictured here, which is an electron microscope, which uses the wave property of the electron. So, for example, if I accelerate my electron to 50% of the speed of light, it gives me a wavelength, which I'm able to use to be able to see right down to the nanoscale. In fact, I can get atomic resolution with that. That's why I went through and told you all about the particle wave duality and so forth, because we use that to be able to do the engineering, and in this case, to be able to see down on those very small scales. So this gives us atomic resolution. And then we get very nice images like this, which is a strontium titanate crystal. And what you're actually seeing there are atoms. So we can use these instruments, these electron microscopes, to do many things, not only to have the eyes to look down on the nanoscale, but we can use them to manipulate the atoms on the atomic scale as well. And some very intelligent researchers at the University of Wisconsin, Madison, and this is why I've got this object here. This is a bucky badger, which is their mascot, which they use for their football matches over there. And what they did is they made a nano version of this little bucky badger. And this badger is so small that you can fit 9,000 of them onto the head of a pin. That's how small that is. So that gives you some indication of how we can control things on that sort of level. And these are actually made up of carbon fibres, incidentally. So if we have this level of control on this very small scale, what does that do in terms of leaving open our engineering and how we design with it? And quite a while ago, in 1959, a very important American physicist called Richard Feynman gave a prediction in terms of what he thought this might look like. And of course, they didn't have the ability to do it then. So this is definitely a prediction. And he said, but I'm not afraid to consider the final question as to whether ultimately in the great future we can arrange the atoms, the way we want, the very atoms all the way down. And he said this in a popular lecture that he gave. And in fact, this is what we can do today. This is our level of control that we have. And from there, we've gone to develop all different types of nanotechnologies. This is probably one of the earliest examples. This was in the late 80s IBM researchers using a special type of electron microscope to grab atoms, in this case, xenon atoms, and to move them around on a nickel surface. And they were able to spell out the words IBM with that. We've since moved on from there to various types of nanotech objects going from layered systems, which is shown here. So very thin atomic layers, in this case, cobalt with a copper layer sandwiched between them both. And this particular structure here can be used to manipulate the spin, which I told you about. That is the intrinsic property of the electrons. And in doing this here, we can apply an electric field to this system, and we can turn on and off how the electrons are aligned across the layers. And what we have invented with that is a memory device, which is used, it's called the GMR effect, and it's used in your iPods. So this technology has come to fruition, and it's actually something which is used in your devices now. We can control how atoms grow on different surfaces. So this is literally a picture of cobalt atoms on a platinum terraced material. And as I was saying, we can arrange these atoms as well. We can put them in different types of structures. We can create very, very small atomic scale, atomic clusters. And we can create these devices, which I have alluded to at the beginning of the lecture, which is this quantum dot. And in this quantum dot here, we have this effect. We can literally, by changing the width of this little space here, we can control these energy levels, we can control the distance between the energy levels, and we can literally get rid of our periodic table of elements and create artificial atoms from this. And that's what we have here. So as a function of the size of the system, so as a function of the size of the box, we're changing the difference between the energy levels. And in doing so, if I'm excited and electron from here to here, and it re-emits, and I get this colour, if we change this width of the box, if we change the size of these particles, we then change the difference between these energy levels, and we get out different colours. There are other types of applications of these nanotechnologies, and because I've spoken to you about the atomic clusters, I'd like to play this little video, which will show you some of the really exciting applications of magnetic cluster systems. The centrepiece of the MagForce nanocancre therapy is the nanoparticle, consisting of iron oxide. The particle is covered by a patented coating, which ensures a good stability and division of the iron oxide particles in the tumour tissue. It additionally supports the process by which the particles are absorbed into the cancer cells. The small size of the particle is decisive for the therapy. The diameter measures some 20 nanometers and is thus 500 times smaller than a red blood cell. One milliliter of the particle solution contains nearly 17 trillion single nanoparticles. This high density makes efficient treatment possible. At the beginning of the therapy, the nanoparticles are injected directly into the tumour. The tumour in this particular case is a glioblastoma, a malignant brain tumour characterized by aggressively growing cells. On the microscopic level, the healthy cells can be seen on the left and the tumour cells on the right. After being injected, the nanoparticles spread out in the spaces between the tumour cells. The patient now enters the therapy device in which an alternating magnetic field is produced, which is of no danger to humans. This field affects a 100,000 times alternation of the magnetic poles within the particles per second, creating warmth which is precisely regulated from outside. The warmth forces the particles into the spaces between the tumour cells which makes it easier for them to be absorbed into the cell. This application is repeated and the thermal effect increases visibly. The particles begin to oscillate, causing the cancer cells to die either from active self-destruction or from swelling until they literally burst. Tumour growth is stopped and the destroyed cells, as well as the nanoparticles, are discharged by the body in a natural process. OK, so that gives you again some indication of the applications of the nanotechnology. Nanotechnology these days is not just restricted to physics, it's not just restricted to engineering. It's moving out now across many different disciplines, chemistry, biology, all working together to create something like this, which is an amazing revolution in terms of potential treatments for cancer. This is a bit of research that I'm also actually involved in as well in terms of designing these very small nanoclusters and optimising their properties to be able to give precisely the amount of energy when it's interacting with an external magnetic field to be able to kill the cancer cell tumour. So there's quite a lot involved in terms of the design process of that. But it's not just, as I said, chemistry, physics and engineering. Again, we're starting with the biology and some very interesting ideas are being put forth in terms of how we can use biological systems. For example, viruses in this case to be able to design new technologies. And this sounds very futuristic, but it's something which we're doing at the University of York and I've got a little clip here from somebody who's also doing this at MIT. Imagine a world where car batteries are assembled by biological organisms. They are non-toxic, biodegradable and very powerful. Step into the world of Dr. Angela Belcher. She walked on this beach during her college years at UC Santa Barbara on a few days when she wasn't busy getting degrees in chemistry, biochemistry, molecular biology and electrical engineering. This is where she got her inspiration for a radical line of research that could change batteries forever. So we're thinking about how to make new technologies. We're going to look at it from a very new perspective. 500 million years ago, when the environment of the ocean changed, organisms that were soft body organisms didn't make hard materials, didn't make shells. But through selection pressure and through changes in the chemistry and the environment, they learned how to make materials like shells. Only a multidisciplinary mind like Angie Belcher's would look at that and think this. And we said, wow, if organisms can make shells, I wouldn't think you could get organisms to make batteries. The idea of teaching organisms to make batteries seems out of this world. But Angie Belcher has found a way. The reason that it's such a special structure is that it's based on nanotechnology. Nanotechnology refers to one of the smallest units of measurement, the nanometer, a billionth of a meter. Like the abalone shell, Angie Belcher wanted her nanobatteries to harness the power and perfection of biological systems. I isolated the proteins that are involved in making the really exquisite structure of the shell. And by looking at the periodic table, I started thinking, well, what about all these other elements? Can these same proteins that work for shells, can they work with other kinds of elements? And in fact, it was pretty amazing they could work on other kinds of elements. So what we had to do was pick an organism that was easy to manipulate and could be propagated on a very short time scale so we picked viruses. The virus, it usually makes you think disease. But in Angie Belcher's lab, it's a hard-working green machine. And then we actually start with about a billion viruses that are all genetically identical to each other. Even though the viruses are identical, they have minute differences the same way identical twins can look and act differently. What Angie Belcher and her students need to know is which of these viruses will bond with a metal oxide material. That's what makes them conduct electricity. Out of a billion, only a tiny handful will succeed. So these are the winners. These are the ones we're gonna keep and test to be able to grow our electrode materials. We take those and we isolate them. These winners are taken for a ride down to Dr. Paula Hammond's lab. Here they'll work 24-7. We can build very, very thin films simply by taking one material which has positive charge along it and another material which has negative charge. The beauty of this virus is that if you put it near a sticky surface, it begins to organize itself in rows. Like bricks and mortar, the viruses stack themselves. Pretty soon, they've built a solid plate. This is the plus side of the virus battery. On the other side, a different virus builds the negative plate. To finish off the battery, tiny wires are attached. And this is the final product, an ultra-thin, ultra-light weight, fully water-based virus battery. This is very exciting. So, I mean, that to me is completely amazing that we can use viruses to build these templates by which we can grow and self-assemble material systems. If you remember what I was talking about, the graphene system, one of the things we'd like to do is we'd like to have control on the nanoscale in terms of the structures that we can make out of that single atomic sheet of carbon. You can imagine that we have nanoscale scissors and we can go to this carbon sheet, which is only one atom thick, and we can cut out some very, very small nanoscale structure. The issue with doing that from going from the top down is that our scissors will not get us a perfect system in terms of how we cut out, in terms of how the edges of that structure is. And nanotechnology is very sensitive to what we have in terms of structure and atoms and what the general environment is like on that scale. So, one alternative is to see if we can get these carbon systems to come together and to self-assemble and to use our understanding of chemistry or biology to get them to assemble into perfect little structures. And so that is really the level of control that we are trying to achieve. This is really the next step in terms of engineering on the nanoscale. As I promised, we've come to a point now where Nanotech 101 should have given you enough information and understanding for us to be able to create some nanotechnology right here. And who believes that this is possible? Do you think that we'll be able to do it? Okay, are you up for it? Okay, good. So, what we're going to need is, we're going to need the quantum mechanic. And so, I thought I would play the role of quantum mechanic. And I've put my overalls here, which I'll just hopefully quickly get into. So, you can see we really do take this seriously almost there. Okay, is that convincing enough? All right, so I'm going to play the role of the quantum mechanic. Oh, the other thing I'm going to need is my spanner. So, I've got the spanner. We're going to need some atoms. Let's see, do I have those available as it stands? I do. So, I have three atoms, which I'm going to put down here. What do you think is the missing bit in this? What was the emphasis on in the talk today? What was driving the nanotechnologies? Oh, electrons, okay. Let's see what we can do about that. That's what we've come so far. We've got the nanosystem, we've got the atoms. Now we have to select the electrons. And I have two electrons here. And I need two volunteers to help me to build the nanotechnology. I've got one person at the back. If you can get out. Hello, Ben, would you like to be, and your name? Amber. So, do you have any preference as to whether you're going to be spin up? So, Ben's going to be spin up, Amber's going to be spin down. Now, as the quantum mechanic, I get to impose on you guys the quantum rules. So, the first thing I'd like you to do, and you've got to remember, you've got to really get into the character of this, because you're negatively charged particles. Okay, so, let's sort of just ask you, start off by asking you a question. How do you feel about being close to each other? Perspective of electron. Repel. Okay. So, do you feel happy or sad? Okay, so we need to show the sad face. Yep, brilliant. But now what I'd like you to do is I'd like to invite you both to come into this nano structure that I've got this three atom system. And I'd like to invite spin down to be here. Thank you, right on the atom. Perfect. And spin up, I'm going to have you here. Okay, and again, like I said, this is serious, this is really exactly what I do in terms of my research, believe it or not. I build these nanostructures, I use quantum theory to do it, and then I get to understand how the electrons feel and try and find ways in which I can manipulate the nanostructure to get the electrons to do what I want. That is to give us the nanotechnologies. So, I'm going to ask you both, how do you feel at this point? You feel all right because you're as far as possible from each other, so we should have our happy face. Excellent, a round of applause for that. Excellent. Mr Spin Up, Ben, I'm going to destroy you from this state here and I'm going to create you again here. So, if you can just position yourself there. And remember I was telling you about the Schrodinger equation. Now, this is exactly what we do in the Schrodinger equation when we tried to model these nanosystems. And I'm going to ask you both, how do you actually feel? Yeah, a little bit uncomfortable. Okay, so somewhere between happy and sad. Now the thing is, in terms of the degrees of freedom, I can actually destroy my spin up here from this atom and recreate my spin up here in this atom. So, if you move across to where Amber is, a little bit squishy on the atom there, how are you both feeling? Really, really sad. Okay, so let's give our electrons a round of applause. And now I'm going to show you how that actually builds nanotechnology and how we've actually created it right here today. So, thank you both very much. I'll take the electrons. Okay, so we had our spin up and spin down electrons and I positioned them inside this nanostructure. So, this is an actual calculation in terms of what I call the percentage happiness for my electrons. So, if we have a look at this here, so even though they said that they were feeling slightly uncomfortable, in terms of the probability of whether we would get them in this particular configuration, the probability is actually highest because it's not only how they are feeling next to each other, it's actually also the degree of freedom that these particles have. So, here we've got our particle and this particle can move from here. So, spin up electron can move from here and it can move there. So, it has some degree of freedom to be able to move within this teeny tiny nanostructure. And because it has this degree of freedom to move, overall, this particular type of configuration ends up being the most probable. Or the electrons tend to be most happy in this configuration here. If they were on the outside, so even though they felt more comfortable being as far apart from each other as possible, if you think about it, we have a little bit of an issue because the next thing in terms of the degree of freedom that they have to move in the nanostructure is that they would end up both being on this center atom. So, that's why in terms of the quantum physics, this particular configuration doesn't weigh as highly as this one here. And this one here, they really didn't like that at all, did they? They didn't like being on the same atom having spin up and spin down. And in fact that costs the nanostructure a lot of energy. So, that's why the measured probability of electron happiness is quite low for that particular configuration. But you might be asking yourself, how do we get nanotechnology from this? Well, if we take what's called a superposition if we have a snapshot which looks at all of these types of configurations and we have one snapshot which takes them all into consideration, we would get something which would look like this. So, a structure which has alternating up, down and up. If we then put a spin up to be a one and a spin down to be a zero, what do you think we have invented? We invented exactly a quantum memory system. So, yes indeed, we did build the technology here today and again, thank you very much to both my electrons for helping out. So, just in summary, I've spoken a lot about nanotechnology. I've spoken a lot about quantum theory which is driving it. And we did meet the aim. I hope you will agree. Of building nanotechnology here today. So, I hope you've all enjoyed the lecture and maybe consider finding the nanotech in you. Thank you very much.