Interplay between strongly correlated quantum Hall states and superconductivity

摘要：电子是带电粒子，两个相互靠近的电子根据库仑定律相互排斥。大量电子的行为可能要复杂得多，有时甚至违反直觉。例如，晶格振动可以将排斥性相互作用转变为吸引力，从而产生超导性，这是一种对电流没有抵抗力的状态。在二维系统中，电子被限制在薄片材料中，在高磁场中甚至可以发展出更奇特的状态。在某些场中，电阻消失，如在超导体中，但横向（霍尔）电阻保持非零并量子化。其中一些状态可能是一种非常特殊类型的超导体，其中电荷是电子电荷的一部分，这在三维世界中是不可能的。经过多年的研究，这些状态仍然知之甚少，主要是因为用于研究这些脆弱状态的工具非常有限。然而，其中一些状态可能具有创建容错量子计算机所必需的特性。过去，在国家科学基金会的支持下，PI小组开发了一种技术，可以在传统超导体和二维电子系统之间形成高质量的电接触。我们的研究小组现在正在使用超导作为一种新工具来探测高磁场下的奇异态，这是一种以前无法通过实验检验的状态。这项研究可能会导致量子比特的发展，量子信息被编码在系统的拓扑结构中。据预测，这种量子比特具有固有的容错性。教育和推广目标包括培训学生参加多学科项目和组织中学生暑期物理夏令营。技术摘要：在所有的实验系统中，高迁移率二维电子气体（2DEG）扮演着一个独特的模型系统的角色，在这个模型系统中，强电子-电子相关性导致在高磁场下形成大量的奇异态，其中一些被预测会形成非常规的超导态。PI小组最近在GaAs中制造高迁移率2DEG的透明欧姆超导触点方面取得了突破，这将以前无法进入的超导体-2DEG界面的实验研究打开了大门。初步结果表明，对量子霍尔效应中库珀对注入的认识有限。研究目标包括详细研究拓扑上不同的超导性和强相关分数量子霍尔效应之间的相互作用，这是一个以前无法进入的领域，令人兴奋的新物理正在等待被发现。这项研究可能会导致开发一个新的平台，在这个平台上可以实现高阶非阿贝尔激励，这是拓扑保护容错量子计算的先决条件。教育和推广目标包括培训学生参加多学科项目和组织中学生暑期物理夏令营。

Non-technical Abstract:Electrons are charged particles, and two electrons brought close to each other repel according to the Coulomb's law. Behavior of a large number of electrons may be much more complex and sometimes counterintuitive. For example, lattice vibrations can change repulsive interactions into attractive resulting in superconductivity, a state with no resistance to electrical current. In two dimensional systems, where electrons are confined to a thin sheet of material, even more exotic states can develop in high magnetic fields. At some fields resistance vanishes, as in superconductors, but transverse (Hall) resistance remains non-zero and is quantized. Some of these states may be superconductors of a very special type, where charges are fractions of an electron charge, something impossible in a three dimensional world. After many years of studies these states are still poorly understood, primarily due to a very limited amount of tools that can be used to investigate these fragile states. Yet some of these states may possess properties necessarily to create fault tolerant quantum computers. In the past with NSF support, the PI's group developed a technology to form high quality electrical contacts between conventional superconductors and two dimensional electron systems. Our research team is now using superconductivity as a new tool to probe exotic states at high magnetic fields, a regime previously not accessible to experimental scrutiny. This research can potentially lead to the development of quantum bits where quantum information is encoded in the topology of the system. Such quantum bits are predicted to be inherently fault-tolerant. Educational and outreach goals include training students in a multidisciplinary program and organization of a Summer Physics Camp for middle school students.Technical Abstract:Among all the experimental systems high mobility two-dimensional electron gases (2DEG) play a unique role of a model system where strong electron-electron correlations lead to the formation of a plethora of exotic states at high magnetic fields, some of them predicted to form unconventional superconducting states. The PI's group's recent breakthrough in the fabrication of transparent ohmic superconducting contacts to high mobility 2DEG in GaAs opens this previously inaccessible regime of superconductor-2DEG interface to experimental scrutiny. Preliminary results indicate the limited understanding of Cooper pair injection into a quantum Hall effect regime. The research objectives include detailed investigation of interplay between topologically distinct superconductivity and strongly correlated fractional quantum Hall effect, a previously inaccessible regime where exciting new physics is waiting to be discovered. This research can potentially lead to the development of a new platform where high order non-Abelian excitations can be realized, a prerequisite for topologically protected fault-tolerant quantum computing. Educational and outreach goals include training students in a multidisciplinary program and organization of a Summer Physics Camp for middle school students.