Electron Spins on Liquid Helium for Quantum Computing

传统计算机性能的不断提高正在接近一些困难的基本障碍。 量子计算是一种新的信息处理模型，它的性能超过了任何传统计算机，至少在某些问题上是如此。 然而，量子计算机很难制造。它们需要精确控制大量小量子系统之间的相互作用，同时防止它们与环境中的任何其他东西相互作用。电子的磁矩（自旋）是小量子系统的有希望的候选者，因为它们与环境的自然相互作用很弱。 传统的电子设备通过控制电子的运动来操作，并且可以利用这种能力来控制电子自旋之间的相互作用。 然而，取代传统电子设备中使用的数千或数百万个电子，量子计算机必须被设计成控制每个电子。这项研究涉及控制漂浮在超流液氦表面上方约10纳米真空中的电子。 据预测，在这些条件下，自旋相干性将比电子在固体中运动时长得多，如在传统的电子器件中。 将进行激发脉冲电子自旋共振测量以测量电子的自旋相干性，或者至少对相干时间施加下限。 实验工作已经表明，具有100个或更少电子的包可以可靠地在氦表面移动。 实验将进行隔离，移动和测量氦表面上的单个电子。 从事该项目的学生将学习技能，使他们成为富有成效的研究人员。

The continuing advance in the performance of conventional computers is approaching some difficult fundamental barriers. Quantum computing is a new model for information processing, which promises performance beyond that possible for any conventional computer, at least for certain problems. However, quantum computers are very difficult to build. They require precise control over the interactions amongst a large group of small quantum systems while preventing them from interacting with anything else in their environment. The magnetic moments (spins) of electrons are promising candidates for small quantum systems since they naturally interact only weakly with their environment. Conventional electronic devices operate by controlling the motion of electrons, and it may be possible to harness this ability to control the interactions between the electrons' spins. However, instead of the thousands or millions of electrons which are used in conventional electronic devices, quantum computers must be engineered to control each individual electron.This research involves controlling electrons floating in a vacuum about10nm above the surface of superfluid liquid helium. It has been predicted that under these conditions the spin coherence will be long much longer than when the electrons are moving in a solid as in conventional electronic devices. Ensemble pulsed electron spin resonance measurements will be conducted to measure the electrons' spin coherence, or at least to put a lower limit on the coherence time. Experimental work has already shown that packets with 100 or fewer electrons can be reliably moved across the surface of the helium. Experiments will be performed to isolate, move, and measure individual electrons on the helium surface. The students working on this project will learn skills to enable them to be productive researchers.