The development of technology and our understanding of the physical world are necessarily deeply intertwined. New understanding in physics leads to the development of new technology, which in turn provides both new tools for studying the physical world, and new challenges for physicists wishing to improve on this technology. In this sense, the impact over the last century of quantum mechanics — the physics of microscopic particles and systems — has been extreme. In the last two decades alone the explosion of technology based on lasers and semiconductor electronics has been staggering, and these devices are now not only central to our daily lives (in the form of computers, entertainment systems, and medical and industrial equipment), but are also important tools in all branches of physics.