Harmonic detection of the Majorana fermion in narrow bandgap InAsSb

窄带隙 InAsSb 中马约拉纳费米子的谐波检测

• 批准号: 1408796
• 负责人: Ian Appelbaum
• 金额: $ 12万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1408796&HistoricalAwards=false
• 关键词: Harmonic; detection; Majorana; fermion; narrow

Non-Technical Abstract:This project will develop an alternative measurement scheme using harmonic generation in a novel hybrid capacitor device aimed to circumvent the fundamental limitations of conventional methods to settle the (still open) question: Has the solid-state "Majorana fermion¨ been seen? This novel state of matter, theoretically predicted to have unusual behaviors, is induced by superconductivity and electron interactions in certain semiconductor structures. Its discovery and manipulation in appropriately-design circuits could lead to the creation of a new kind of quantum computer which is essentially immune to decoherence.Technical Abstract:This project will develop a measurement technique utilizing harmonic generation in a novel hybrid capacitor device to measure global density of states of a low-dimensional electronic material without perturbative ohmic contact. It is motivated by a need to definitively identify zero-bias tunnel-transport anomalies in spin-orbit-coupled one-dimensional superconductors as possible signatures of a predicted topological electronic excitation localized to wire endpoints called the "Majorana fermion¨.Briefly, the electrostatic potential of an intermediate material floats between the capacitor electrodes, and can exchange electrons with one (grounded) electrode via tunneling. Capacitive coupling to the top electrode at voltage V(t) induces a voltage drop between the floating material and the bottom grounded electrode, driving elastic tunneling which is sensitive to the global density of states. If the capacitive impedance at the driving frequency is comparable to the characteristic (voltage-dependent) tunnel resistance, the nonlinear conductance spectrum components will be encoded into the higher harmonic response of the device.Importantly, the research team intends to fabricate the nanowires using high-quality InAsSb (from collaborators at nearby Adelphi Army Research Laboratory), which has a lower bandgap than either of the binary constituents InAs or InSb. The team will work toward confirming that it also has a lower effective mass, higher g-factor, and larger spin-orbit interaction (as predicted by k-dot-p theory. All of these parameters will substantially optimize the Majorana formation and its topological protection to enhance the possibility of detection using our harmonic generation measurement.

非技术摘要：该项目将开发一种在新型混合电容器装置中使用谐波产生的替代测量方案，旨在绕过传统方法的基本限制，以解决(仍未解决的)问题：固态“Majorana费米子”被看到了吗？这种新的物质状态，理论上被预测具有不寻常的行为，是由某些半导体结构中的超导和电子相互作用引起的。它的发现和在适当设计的电路中的操纵可能导致一种新型的量子计算机的诞生，这种计算机本质上不受退相干的影响。技术摘要：本项目将开发一种利用新型混合电容装置中的谐波产生来测量低维电子材料的全局态密度的测量技术，而不需要微扰欧姆接触。它的动机是需要明确地识别自旋轨道耦合的一维超导体中的零偏压隧道输运异常，作为预测的拓扑电子激发的可能信号，该信号定位于导线端点，称为马约拉纳费米子。简单地说，中间材料的静电势漂浮在电容电极之间，并可以通过隧道与一个(接地)电极交换电子。在电压V(T)下与上电极的电容耦合在浮动材料和下接地电极之间引起电压降，从而驱动对全局态密度敏感的弹性隧穿。如果驱动频率下的电容阻抗与特性(与电压相关)的隧道电阻相当，则非线性电导光谱分量将被编码为器件的高次谐波响应。重要的是，研究小组打算使用高质量的InAsSb(来自附近阿德尔菲陆军研究实验室的合作者)来制造纳米线，它具有比二元成分InAs或InSb更低的带隙。该团队将致力于确认它也有更低的有效质量，更高的g因子，以及更大的自旋-轨道相互作用(正如k-点-p理论所预测的那样)。所有这些参数将大大优化Majorana形成及其拓扑保护，以增强使用我们的谐波产生测量进行检测的可能性。