Phase Competition and Domain Textures in the Fractional Quantum Hall Effect

摘要：本项目研究在半导体多层结构中观察到的一种称为分数量子霍尔效应（FQHE）的基本物理现象。利用新型的高灵敏度光学技术对暴露在强磁场下的超高纯度半导体进行了研究。这种低无序半导体和新型测量方法的结合可以检测到这些材料中电子之间相互作用的激发模式的极小信号。传统的磁输运测量方法不足以检测这些发生在大部分材料中的激发。对这些低洼激发的研究为电子系统中的基本相互作用提供了重要的见解，并对量子计算技术的发展产生了后续影响。该项目为研究生和本科生以及博士后研究人员提供前沿科学培训。计划开展外联活动，以吸引包括妇女和少数民族在内的各种群体。技术摘要：本项目通过实验探测分数量子霍尔效应（FQHE）体电子流体中的低空激发，以了解拓扑保护电子流体中强电子相关的物理特性。虽然FQHE中的大部分相关物理都是根据复合费米子准粒子来理解的，但最近的理论引入了内部几何自由度，由于朗道内部电子库仑相互作用，它影响了大磁场中的轨道运动。这些相互作用产生了新颖的效应，这种效应在低洼激发的分散上有独特的表现。已知FQHE流体的大部分是无序的，其中FQHE流体的域与二维（2D）电子流体的其他相域共存。光学方法将用于识别FQHE流体的大区域，其中低洼激发具有类似于均匀系统的动量色散。采用PI组开发的先进共振非弹性光散射方法研究了低洼模式。在朗道能级填充nu=1/3时，将着重于识别几何理论预测的角动量L=-2的手性重子。许多拟议的研究工作将集中在第二个朗道能级的FQHE状态上，这个状态是朗道能级填充因子5/2和7/3的有趣的FQHE状态的宿主。用光学方法研究倾斜磁场中涌现向列相及其与体内FQHE相的竞争。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical Abstract:This project investigates a fundamental physics phenomenon called fractional quantum Hall effect (FQHE), which is observed in semiconductor multilayer structures. The investigation is performed on unique ultra-high purity semiconductors exposed to high magnetic fields using novel high sensitivity optical technique. This combination of low-disorder semiconductors and novel measurement methods enables detection of extremely small signals of excitation modes that accompany interactions between electrons in these materials. Traditional methods of magneto-transport measurements are insufficient for detecting these excitations that occur in the bulk of these materials. Studies of these low-lying excitations provide important insights on fundamental interactions in electronic systems with subsequent impacts on the development of quantum computation technology. The project provides training in cutting-edge science to graduate and undergraduate students as well as postdoctoral researchers. Outreach activities are planned to attract diverse group including women and minorities.Technical Abstract:The work proposed in this project experimentally probes low-lying excitations in the bulk electron fluids of the fractional quantum Hall effect (FQHE) to understand physics of strong electron correlation in topologically protected electron fluids. While much of the correlation physics in the FQHE is understood in terms of composite fermion quasiparticles, more recent theories introduced an internal geometrical degree of freedom that impacts orbital motion in the large magnetic field due to intra-Landau electron Coulomb interactions. These interactions result in novel effects that uniquely manifest on the dispersions of low-lying excitations. The bulk of the FQHE fluids is known to be disordered in which domains of FQHE fluid coexist with domains of other phases of the two-dimensional (2D) electron fluid. Optical methods will be used to identify large domains of FQHE fluid in which the low-lying excitations have momentum dispersions that are like those of a uniform system. The low-lying modes are studied by advanced resonant inelastic light scattering methods developed in the group of the PI. At Landau level filling nu=1/3 the measurements will be focused on identification chiral gravitons of angular momentum L=-2 predicted by geometrical theories. Much of the proposed research efforts will be focused on the FQHE states of the second Landau level that is host to intriguing FQHE states at Landau level filling factors 5/2 and 7/3. In tilted magnetic field emergent nematic phases and their competition with FQHE phases in the bulk will be studied by optical methods.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.