Cold Atoms, Cold Molecules, and Spectroscopy

在该补助金下开展的工作包括两个部分。其中一个组成部分将涉及玻色-爱因斯坦凝聚体中冷原子系综的理论建模，其中所有原子都处于最低量子能级，温度低于绝对零度。最近的许多实验，包括在斯托尼布鲁克的一些实验，都是在这样的原子系综上进行的。这些实验可以以可控的方式模拟晶体固体（例如半导体或超导体）中的周期性势。需要解决的一个问题是，当施加周期性势时，原子是否保持在最低量子态，也许是突然的，或者是否诱导了激发。理论工作将有助于解释最近在这一点上的实验观察。另一部分涉及世界范围内几个实验室的工作，这些实验室致力于生产超冷双原子分子，也是在纳开尔文温度下。近年来，我们一直在分析双原子分子的光谱数据，以便能够告诉实验学家使用什么激光波长来诱导两个冷原子结合在一起成为一个冷分子。下一步的工作是分析核自旋结构的影响关于这项工作的更广泛的影响，可以说，原子和双原子分子达到极低的温度允许人们克服在正常温度下的平均效应，当大量的量子能级被占据时。通过选择处于最低量子态的粒子，可以获得关于它们的相互作用和行为的更精确的信息。通过改变施加在冷原子上的条件，可以更好地理解复杂的自然发生系统中发生的效应。例如，周期性激光场可以模拟晶格中的周期性电势，但是在晶格振幅和波长的范围内。这已经对高温（50开尔文以上）超导现象以及原子核内复杂的相互作用产生了新的见解。超导体现在被用于许多研究应用中。它们在高电流密度地区的电力传输中的使用可以提高美国的效率。S.电网

The work to be performed under this grant consists of two components. One component will involve theoretical modeling of ensembles of cold atoms in a Bose-Einstein condensate, in which all atoms are in the lowest quantum level, at temperatures less than a microdegree absolute. Many recent experiments, including some at Stony Brook, have been performed on such atomic ensembles when placed in a periodic potential. These experiments can mimic, in a controllable way, the periodic potential in a crystalline solid, such as a semiconductor or superconductor. One question to be addressed is whether the atoms remain in the lowest quantum state when the periodic potential is applied, perhaps suddenly, or whether excitations are induced. The theoretical work will help to interpret recent experimental observations on this point. The other component pertains to work in several laboratories world-wide directed to the production of ultra-cold diatomic molecules, also at nanoKelvin temperatures. In recent years, we have been analyzing spectroscopic data on diatomic molecules to be able to tell experimentalists what laser wavelengths to use to induce two cold atoms to bind together into a cold molecule. The next stage of the work is to analyze effects of nuclear spin structure (analogous to effects that are used in nuclear magnetic resonance imaging), which become predominant in certain regimes.With regard to the broader impact of this work, it can be said that the attainment of extremely low temperatures of atoms and now of diatomic molecules allows one to overcome averaging effects at normal temperatures, when a vast number of quantum levels are occupied. By selecting particles in the lowest quantum state, it is possible to obtain much more precise information on their interactions and on their behavior. It has been possible to better understand effects that occur in complicated naturally occurring systems by being able to vary the conditions imposed on the cold atoms. For example, a periodic laser light field can mimic the periodic potential in a crystalline lattice, but over a range of lattice amplitude and wavelength. This has already produced new insights into phenomena such as high temperature (above 50 Kelvin) superconductivity and also into the complicated interactions within atomic nuclei. Superconductors are now used in many reseach applications. Their use in electrical power transmission in areas of high electrical current density could improve the efficiency of the U. S. power grid.