Theoretical research in nonlinear and quantum optics

点击翻译按钮获取中文摘要

Light and matter: How do they interact? This is a proposal for a research program to investigate some of the quantum mechanical subtleties of photons and electrons -- the particles of light and electricity -- that arise when there are many electrons around, because the matter is condensed, and many photons around as well, due to the light being very intense. Remarkable things can happen. The presence of the electrons can cause some of the photons to split into two photons. These new photons are "entangled," as is said in the jargon of quantum mechanics, neither photon really being quite independent of the other even if they would propagate kilometres away from each other. This entanglement makes them a resource for processing information. But to do that we need many of them, and should be able to control them: they should be on a "chip," just as are the electrons we control to use for information processing. How do we make the photons there, control them there, and adjust their properties so they are interesting and useful? Will all the imperfections on a chip destroy their subtle connection with each other? What if one scatters off the chip? How would we do "quality control" on these chips if we were to make them? Can we add special elements to the chip that will give us more special photon states? Or could we just combine standard elements in a special way to get those special states?The electrons can behave in strange quantum mechanical ways too. When an electron is in a solid and a strong electric field is applied, it responds with an "effective mass" that can be quite different than its mass in free space, and reflects the effects of the underlying lattice. But it doesn't respond with this effective mass right away. As the very first it responds with its free space "bare mass." How does this happen? How long does it take for the "effective mass" to emerge? Are there other quantities that behave like that, taking their time to settle down when a force is applied? Will these effects be important in ultrafast electronics? If instead we let light act on the electrons in a solid, since quantum mechanics allows different possibilities to interfere with each other, just as water waves can, we can use the light to generate an interference that will send electrons in one direction or another, just as we choose. Can we use this to control currents in new nanostructure devices? Or at least to study how electrons move in these materials, by shooting them first in one direction and then in the other? Can we shoot spins too? This is using the light to control the electrons. But if the light is very intense will it be affected by the electrons in ways other than by making some of the photons split? Can we use these other effects to control the light, or change its color? Can we do this all on a chip too? Will novel materials help? Do we have all the underlying concepts we need to address these issues? As material and laser science progresses, leading to smaller and smaller solid state structures and shorter and shorter optical pulses, these kinds of phenomena will be crucial as photonics and electronics merge into a single field that may have a profound impact on both our science and technology. Behind all of them are fundamental issues in physics.