Measurements of Current-Phase Relationships in Josephson Junctions

约瑟夫森结电流相位关系的测量

• 批准号: 1708914
• 负责人: Kathryn Moler
• 金额: $ 43.94万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-10-01 至 2021-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1708914&HistoricalAwards=false
• 关键词: Measurements; Current; Phase; Relationships; Josephson

Non-technical abstract: Quantum devices have exceptional promise for computation, communication, and sensing. To realize this potential, scientists and engineers must find the right physical system in which to implement quantum bits, called qubits, with sufficiently low error rates. Small superconducting devices are one of the most promising candidates for building physical devices that function as qubits. This research seeks to address fundamental questions about the nature of small superconducting devices. The researchers make sensitive magnetic measurements to detect the current flowing through a superconducting device to determine whether it has a conventional superconducting state or an unconventional, "topological" superconducting state. Topological superconducting state are states that host special modes at their boundaries, called Majoranas modes. Qubits based on these Majorana modes could greatly reduce errors compared to other types of qubits. Technical abstract:The proposed operation of topological qubits is based on a special zero-energy modes known as Majorana modes. The objective of this research is to experimentally demonstrate the existence of Majorana modes using a new generation of fast, highly sensitive Superconducting Quantum Interference Device (SQUID) sensors. The two most important properties are the current-phase relation, a fundamental relation that will have conclusive signatures of Majoranas if they are present and stable, and the parity lifetime, which determines how long the Majorana states are stable. The experiments address longstanding questions in conventional (non-topological) mesoscopic superconductivity, such as the behavior of tunable few-mode junctions with perfect transmission. They also address newer, more urgent questions in topological devices, such as in which systems Majorana fermions exist and for how long their properties are stable. The realization and control of Majoranas would have great foundational significance as an experimental instance of engineered particles with non-Abelian statistics and could also enable certain quantum information technologies. The activities additionally foster the development of fast, ultrasensitive magnetic measurement techniques that are relatively noninvasive. The researchers engage actively in community and outreach activities designed to provide role models and experiential learning to science students at all levels. Student and postdoctoral researchers involved in the research are well-trained in nanotechnology, cryogenics, quantum science, and precision measurements, and are prepared for a lifetime of contributions both as educators and as scientists.

非技术摘要：量子设备在计算、通信和传感方面有着非凡的前景。为了实现这一潜力，科学家和工程师必须找到合适的物理系统，在其中实现称为量子比特的量子比特，并且错误率足够低。小型超导设备是建造起量子比特功能的物理设备的最有前途的候选者之一。这项研究试图解决有关小型超导设备性质的基本问题。研究人员进行了灵敏的磁测量，以检测流经超导装置的电流，以确定它是处于常规超导状态还是非传统的“拓扑”超导状态。拓扑超导态是在其边界上存在特殊模的状态，称为Majoranas模。与其他类型的量子比特相比，基于这些Majorana模式的量子比特可以大大减少误差。技术摘要：提出的拓扑量子比特操作是基于一种特殊的零能模式，称为Majorana模式。这项研究的目的是使用新一代快速、高灵敏度的超导量子干涉器件(SQUID)传感器来实验证明Majorana模的存在。两个最重要的性质是电流-相关系，这是一个基本关系，如果马约拉纳存在和稳定，它将具有马约拉纳的决定性特征，以及奇偶寿命，它决定马约拉纳态稳定的时间。这些实验解决了传统(非拓扑)介观超导电性中长期存在的问题，例如具有完美传输的可调少数模结的行为。它们还解决了拓扑设备中更新、更紧迫的问题，例如在哪个系统中存在Majorana费米子，以及它们的性质稳定了多久。作为非阿贝尔统计工程粒子的实验实例，Majoranas的实现和控制将具有重大的基础意义，并可能使某些量子信息技术成为可能。这些活动还促进了相对非侵入性的快速、超灵敏磁测量技术的发展。研究人员积极参与社区和外联活动，旨在为各级理科学生提供榜样和体验式学习。参与这项研究的学生和博士后研究人员在纳米技术、低温、量子科学和精密测量方面都接受过良好的培训，并为作为教育工作者和科学家的终身贡献做好了准备。