Quantum dynamics: Light and matter

量子动力学：光与物质是如何相互作用的？这是一项研究光子和电子的一些量子力学微妙之处的提议。光子和电子是当周围有许多电子时产生的光和电的粒子，因为由于光线非常强烈，物质和周围的许多光子都是凝聚的。*非凡的事情可能会发生。一些光子可以分裂成两个光子，或者两个光子可以反应形成两个新的光子。这些新的光子可以是“纠缠的”，没有一个光子真正独立于另一个，即使它们彼此传播了几公里远。许多这样的纠缠对可以形成“压缩真空”，而且还有比这更微妙的光态。它们的非经典性使它们成为量子信息处理的重要资源。但要使用它们，我们需要能够控制它们。它们应该在“芯片”上，就像我们用于信息处理的电子一样。我们如何对光子做到这一点，并让它们在存在散射和其他现实世界缺陷的情况下保持其非古典性？我们可以用它们做什么？电子也可以以奇怪的量子力学方式运行，特别是在光与它们相互作用的情况下。在量子力学中，不同的可能结果可能会相互干扰，就像水波一样，我们可以利用这一点，让光速使电子朝一个或另一个方向加速，就像我们选择的那样。然后，就像一辆引擎关闭的汽车一样，它们将开始减速。但扮演道路和空气阻力的角色将是与其他电子和声音粒子散射。通过这样的实验，我们能了解固体中的所有这些“准粒子”吗？我们能制造一种用光控制电力的有用设备吗？如果一个电子有一个确定的速度，量子力学要求它的位置是不确定的。那么，我们如何看待一个特定位置上的电场如何“驱动”电子呢？像电阻和电容这样的基本概念有意义吗？随着材料和激光科学的进步，导致固态结构越来越小，光脉冲越来越短，随着量子光子学和电子学合并成一个可能对我们的科学和技术产生深远影响的单一领域，这些现象将是至关重要的。在所有这些问题的背后，都是物理学的基本问题。

Quantum dynamics: Light and matter******How do light and matter interact? This is a proposal for research into 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. Some of the photons can split into two photons, or two photons can react to form two new photons. These new photons can be “entangled,” with neither photon really being independent of the other even if they propagate kilometres away from each other. Many such entangled pairs can make a “squeezed vacuum,” and there are states of light even more subtle than that. Their “non-classicalness” makes them an important resource for quantum information processing. But to use them we need to be able to control them. They should be on a “chip,” just as are the electrons we use for information processing. How do we do that for photons and have them preserve their non-classicalness in the presence of scattering and other real-world imperfections? And what is the range of things we can really do with them?******The electrons can behave in strange quantum mechanical ways too, especially if light interacts with them. In quantum mechanics different possible outcomes can interfere with each other, just as water waves can, and we can use this to make light speed electrons up in one direction or another, just as we choose. Then, like a car with its engine turned off, they will start to slow down. But playing the role of road and air resistance will be scattering with other electrons, and with particles of sound. Can we learn about all these “quasi-particles” in a solid by such experiments? Can we make a useful device using light to control electricity? And if an electron has a definite velocity, quantum mechanics requires that its position is not definite. How then do we think about the way an electric field at a particular position “drives” the electron? Do elementary concepts like resistance and capacitance make sense?******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 quantum 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.