 The building blocks of our universe from atoms to fundamental particles follow behave according to the rules of quantum physics. Those are very different from the rules of your everyday life, which we call classical physics. For instance, where you or I expect to be in one place at any one time, the atoms in my laboratory are perfectly happy to be in two points at time. A computer is a physical system. My laptop at home works by pushing electrical signals around a chip. The computational power of that device and the rules it follows are all classical rules. If you were the atom in my laboratory, you might wonder, why restrict me like that? Why would I use classical rather than these quantum rules I know and love? And that is a restriction. There are problems which we know scale as the problem size gets bigger. They scale exponentially on a classical computer, rapidly hitting the edge of the universe, where a quantum computer would still be able to finish in a reasonable amount of time. How and where does the quantum system find its power? In some sense, it comes from the fact that quantum computers can process lots of inputs in parallel. But that has to be allied to the ability to combine these inputs, and that happens through the wave-like interference of quantum mechanics. And if we can do that in these special ways, combine these answers or produce this interference of a strong answer from lots of inputs, then we can make certain computations fast. One of those is in public key distribution. We would be able to break public key distribution, and that's a major security problem, and so governments have been interested in quantum computing since the 1990s. But other problems are available, and one is in calculating quantum systems themselves. So some of the molecules that we have today, FOMOCO would be one of them, are quantum systems in themselves, and they are better done on a quantum computer than a classical computer. Now, FOMOCO is interesting because it allows plants to extract ammonia at comfortable conditions, and that's in stark contrast to the industrial methods we have today. But quantum seems to be possible in more areas, and what we firmly believe, or I firmly believe, is that once people get hold of a quantum computer, they will think of new things to do with it. In 1940s, people had classical computers doing cryptography and physics, but now classical computers do everything for us, including your smartphone apps. What would a quantum computer look like? Well, likely it would look very mundane. Maybe a supercomputer of some type, a row of black boxes attached to power and to the network. But at its heart, a quantum computer has to have quantum systems. Whether these be single atoms, single electrons, currents in superconductors, or defects in some material like diamond. We don't yet know what the winner is going to be of all of these, and we don't yet know when we're going to get to that winner. The systems that I like to use are individual atoms. These are controlled using laser light, and the control we can achieve is unmatched in its precision. And these have been used to make few quantum bit quantum computers with five quantum bits and about a thousand operation. And in the near future, what we have coming is 50 to 100 quantum bits. And that's interesting for us in physics because a classical computer would no longer be able to compute what that system is doing. But we have a problem that the lack of control we'll have over those quantum systems that probably we won't be able to give you useful computers at that scale. Conversely, what that's going to mean is we have to actually make much larger systems. If we make larger systems, we can correct errors, and that means that a useful quantum computer probably needs one million bits and 10 to the 17 operations. And that's a huge scaling beyond what we have today. So we have to take new approaches. In my field, we go from trapping systems to trap our atoms, which consist of machined metal, making microchips that can be mass engineered and which can integrate control. And that's something that we're working on, but there are challenges and this is still a research challenge. So one of the challenges would be in optics. We have to deliver light to these atoms to do our control. Lots of wonderful optics exists at telecommunications wavelengths, 15-15 nanometers. But our atoms are extremely specific about the color of light that they interact with. So what we have to do is transfer all these wonderful technologies down into completely different range of colors. That needs new materials and it needs new techniques. But work is happening. So we see now ultraviolet fibers that have been brought up from our quantum computing community and chips now where the light is guided through the chip to do quantum control. So this is really happening. The quantum computer is coming. We don't know what form it will take, ultimately. I think we could safely say that we don't know how long we're going to take to get there. But we should remember that it's going to have power beyond any computational device that we have today. A power which I think we won't be able to fully utilize until the children of tomorrow really start playing with these systems. Thanks for your attention.