Quantum Tunneling in One- and Three-Dimension Systems

9310260古德金德这个实验和理论相结合的项目将研究一维模型系统和三维模型系统中的量子隧道效应。一维系统由电子在氦表面的像势相关联的浅势垒中隧穿而成。三维系统是固体He-4。氦上的电子代表了一个模型系统，其中隧穿速率可以作为外加电场和电子密度的函数来测量。该系统适合用一维含时薛定谔方程来研究。固体He-4是自然界中最简单的固体，因此它的性质提供了适用于所有固体的基本理解。在He-4中，像空位这样的晶格缺陷被认为是离域的，因为它们能够在周期晶格的势极小值之间隧穿。然而，关于它们的浓度和性质的实验证据是有限的，也是不确定的。拟议的研究旨在解决两个系统中的某些悬而未决的问题。此外，随着微电子设备变得更小，以及在紧密间隔的结构之间进行隧道传输的可能性更大，隧道现象可能会引起技术上的兴趣。这是一个实验和理论相结合的实验，将研究两个模型系统中的量子隧穿。量子隧道类似于早上在前院的车库外找到你的车，尽管它在前一天晚上被锁在里面。这种宏观事件不太可能发生，但如果汽车和周围环境缩小到原子尺寸，隧道效应就会成为一种可测量的现象，特别是在非常低的温度下。在这项工作中，一个模型系统由电子通过势垒隧道离开表面组成。在另一个模型系统中，固体中的氦原子从晶格位置(车库)隧道到缺陷(前院)。在这两种情况下，都有理论和实验性质的根本问题需要解决。此外，随着微电子设备变得更小，以及在紧密间隔的结构之间进行隧道传输的可能性更大，隧道现象可能会引起技术上的兴趣。***

9310260 Goodkind This combined experimental and theoretical project will study quantum tunneling in a one-d model system and a three-d model system. The one-d system consists of electrons tunneling out of the shallow potential well associated with their image potential at the surface of helium. The three-d system is solid He-4. Electrons on helium represent a model system where tunneling rates can be measured as a function of applied electric field and electron density. This system is appropriate to study using the one-d time-dependent Schrodinger equation. Solid He-4 is the simplest possible solid in nature so that its properties provide fundamental understanding applicable to all solids. In He-4, lattice defects such as vacancies are expected to be delocalized as a result of their ability to tunnel between potential minima of the periodic lattice. However, experimental evidence about their concentration and their properties is limited and inconclusive. The proposed research is intended to resolve certain outstanding issues in both systems. Further, the tunneling phenomena are potentially of technological interest as microelectronic devices become smaller and tunneling between closely spaced structures more likely. %%% This is a combined experimental and theoretical which will study quantum tunneling in two model systems. Quantum tunneling is analogous to finding your car outside your garage in the front yard in the morning, even though it was left locked inside the night before. This macroscopic event is very unlikely, but if the car and surroundings are shrunk to atomic dimensions, tunneling becomes a measurable phenomenon, particularly at very low temperatures. In this work, one model system consists of electrons tunneling through a potential barrier to leave a surface. In the other model system, helium atoms in the solid tunnel from lattice sites (garages) to defects (front yards). In both cases, there are fundamental issues of both a theore tical and experimental nature that need to be resolved. Further, the tunneling phenomena are potentially of technological interest as microelectronics devices become smaller and tunneling between closely spaced structures more likely. ***