NMR Study of Liquid Crystals

这项关于液晶的核磁共振研究的项目将涉及两个新的进展：(1)使用~(13)C核磁共振测量长程偶极耦合常数；(2)使用液晶进行核磁共振量子计算。在(1)方面，将对固体核磁共振中现有的脉冲序列和新开发的方法进行修改以提高性能，并将合成和研究其他类型的液晶，为判断理论模型，特别是分子动力学模拟的成功提供最严格的实验标准。在区域(2)中，核磁共振量子计算的前提要求使用除了一个能级以外所有能级的布居都相等的伪纯量子态来代替纯量子态。为了为具有三个或更多量子比特的系统准备这些赝态，将开发新的方法来克服现有的复杂脉冲序列的方法，这些方法具有许多步骤，使得这些实验变得非常困难。多频辐射将通过布居转移来制备赝势态，从而大大减少了所需的步骤。另一种有待探索的方法是利用赝态对及其扩展来研究具有4到7个量子比特的液晶系统。主要的重点将是发展核磁共振、方法学和寻找合适的自旋系统，而不是设计算法来解决需要复杂量子计算的问题。这个液晶研究项目是非常多学科的，为学生提供了广泛的培训机会，领域包括合成化学、量子物理、建模和模拟，以及涉及液晶作为显示器和量子计算光学材料的应用技术。由于这些领域在行业中处于高度优先地位，这些学生在就业市场上具有很强的竞争力。

This project on Nuclear magnetic Resonance (NMR) studies of liquid crystals will involve two new thrusts: (1) the use of carbon-13 NMR to measure long range dipolar coupling constants, and (2) the use of liquid crystals for NMR quantum computing. Regarding area (1), the existing pulse sequence being used with newly developed methods in solid-state NMR will be modified to improve performance, and other types of liquid crystals will be synthesized and studied to provide the most stringent experimental criteria for judging the success of theoretical models, especially molecular dynamics simulations. In area (2), the premise of NMR quantum computing requires that pseudopure quantum states, for which the populations of all energy levels but one are equal, be used instead of pure quantum states. To prepare these pseudospure states for systems with three or more quantum bits, new approaches will be developed to overcome the existing methods for elaborate pulse sequences with many steps that make these experiment very difficult. Multifrequence radiation will be used to prepare the pseudopure states via population transfer to greatly reduce the number of steps needed. Another method to be explored is the use of pairs of pseudopure states and their extension to study liquid crystal systems with 4 to 7 qubits. The main emphasis will be the development of NMR, methodology and the search for proper spin systems rather than devising algorithms to solve problems requiring complicated quantum computation.%%%This liquid crystal research project is very multidisciplinary involving a broad scope of training opportunities for students in areas that include synthetic chemistry, quantum physics, and modeling and simulation, as well as applied technologies involving liquid crystals as optical materials for displays and for quantum computing. Because these areas of high priority in industry, these students are highly competitive in the job market.