Collaborative Research: Design and modeling of novel superconducting circuits with coherent phase slips

合作研究：具有相干相滑的新型超导电路的设计和建模

• 批准号: 1560732
• 负责人: Alex Levchenko
• 金额: $ 8.35万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1560732&HistoricalAwards=false
• 关键词: Collaborative; Research; Design; modeling; novel

Superconductivity is a quantum phenomenon that manifests itself as an abrupt disappearance of resistivity in certain materials as temperature is lowered below their critical temperature. Recent advances in the nanometer size fabrication, materials science and high precision measurements made it possible to investigate a variety of novel superconducting nanosystems, which were almost unthinkable only a few years ago. Specifically the studies of quantum transport phenomena in nanoscale superconducting wires and circuits made of them are rapidly emerging as one of the central themes of modern physics and engineering. As wire is made narrower, a variety of intriguing quantum effects becomes apparent. Strong spatial confinement leads to intricate electron correlations that influence superconducting properties of the structure. Ultimately superconductivity could be gradually extinguished and some wires may display pronounced insulating behavior, leading to the so-called superconductor-insulator transition. Superconductors are extremely attractive systems from the point of view of future applications as they could become elementary building blocks for memory bits of quantum computers and other devices operating on coherent quantum tunneling events. The main aim of this joint project is to harness the power of quantum coherence, address the urgent problems of nanoscale-circuit-superconductivity at the frontier of current research, and discover new physics in this exciting field. Our approach will be to combine the expertise of a condensed matter theorist and an experimentalist both having extended experience in related fields. The collaborative structure of the research will provide a rich environment for training students in a broad spectrum of experimental nanoscience and theoretical condensed matter physics. Educational aspects will be further integrated through the development of courses directly related to the proposed research and through research-related seminars, science olympiads, and meetings that target high-school teachers.The goal of the project is to study emergent quantum transport phenomena in the modern nanoscale superconducting circuits driven far from equilibrium and populated with coherent phase slips to reveal the ultimate fate of superconducting correlations in the new domain of external conditions and environments. A substantial part of the proposed research is devoted to stochastic kinetics of the coherent phase slips in superconducting nanowires, nanowire-bridged resonators, and interferometers. The focus in on the mutual role of microwave bias and a magnetic field on the reentrant superconductivity, statistics of the supercurrent switching, bi-stability and current-voltage characteristics, and a study of even-odd parity effects for the phase slip tunneling events. Suggested studies of the excess shot noise, carried across the superconducting transition, will provide additional insights into the microscopic mechanisms of the relaxation and fluctuations. The project also dwells into the new area of exploring proximity-induced superconductivity between superconducting and semiconducting heterostructures that host topological order. This research direction aims to answer the key questions concerning robustness and stability of the topological protection to effects of interactions, disorder and other relevant perturbations. The long-term goal of this project is to develop novel superconducting qubits with coherent phase slips for quantum circuit electrodynamics applications. The proposed architecture designs are based on the phase-slip-junction, the phase-slip-oscillator and an alternative device based on the supercurrent carrying inductor with tunable nonlinearity. The success and completion of this proposal will be of value for the technological advances in the information processing and the photon detection. The technical and theoretical methods that will be developed as a part of this proposal are relevant to a much wider class of problems in the quantum physics of many-body systems. The results of the proposed work will be widely disseminated in publications, seminars, colloquia and conference presentations. Students working under this project will receive extensive training by studying modern aspects of the condensed matter physics, developing new conceptual approaches to nonequilibrium superconducting systems and pursuing original research. As a part of the diversity and educational initiatives PIs will expand research opportunities for the undergraduate students of underrepresented groups and contribute to the science olympiad interscholastic competition program.

超导是一种量子现象，当温度低于临界温度时，某些材料的电阻率会突然消失。近年来在纳米尺寸制造、材料科学和高精度测量方面的进展使得研究各种新型超导纳米系统成为可能，这在几年前几乎是不可想象的。特别是纳米级超导导线及其构成的电路中的量子输运现象的研究正迅速成为现代物理学和工程学的中心主题之一。随着电线变得更窄，各种有趣的量子效应变得明显。强空间约束导致复杂的电子相关性，影响结构的超导性质。最终，超导性可能逐渐消失，一些电线可能表现出明显的绝缘行为，导致所谓的超导体-绝缘体过渡。从未来应用的角度来看，超导体是极具吸引力的系统，因为它们可以成为量子计算机和其他在相干量子隧道事件上运行的设备的存储位的基本构建块。这个联合项目的主要目的是利用量子相干性的力量，解决当前研究前沿的纳米级电路超导性的紧迫问题，并在这个令人兴奋的领域发现新的物理学。我们的方法是结合凝聚态物质理论家和实验家的专业知识，他们都在相关领域有丰富的经验。该研究的协作结构将为培养学生在实验纳米科学和理论凝聚态物理的广谱提供丰富的环境。教育方面将通过开发与拟议的研究直接相关的课程以及通过与研究有关的研讨会、科学奥林匹克竞赛和针对高中教师的会议进一步整合。该项目的目标是研究现代纳米级超导电路中出现的量子输运现象，以揭示在新的外部条件和环境下超导相关的最终命运。在超导纳米线、纳米线桥式谐振器和干涉仪中，相干相滑移的随机动力学研究占了相当大的一部分。重点研究了微波偏压和磁场对可重入超导性的相互作用、超导开关的统计、双稳定性和电流-电压特性，以及相滑移隧道事件的奇偶宇称效应的研究。对超导跃迁过程中携带的过量散粒噪声的建议研究，将为弛豫和波动的微观机制提供额外的见解。该项目还探讨了探索超导和半导体异质结构之间邻近诱导超导的新领域，这些异质结构具有拓扑秩序。本研究方向旨在回答拓扑保护在相互作用、失序和其他相关扰动作用下的鲁棒性和稳定性等关键问题。该项目的长期目标是为量子电路电动力学应用开发具有相干相位滑移的新型超导量子比特。所提出的结构设计是基于相滑结、相滑振荡器和基于可调谐非线性的超电流电感的替代器件。本课题的成功和完成对信息处理和光子探测的技术进步具有重要意义。作为本提案的一部分，将发展的技术和理论方法与多体系统量子物理学中更广泛的问题相关。拟议工作的结果将在出版物、研讨会、座谈会和会议发言中广泛传播。在这个项目下工作的学生将通过学习凝聚态物理的现代方面，开发非平衡超导系统的新概念方法和追求原创性研究来接受广泛的培训。作为多样性和教育计划的一部分，pi将为代表性不足的群体的本科生扩大研究机会，并为科学奥林匹克校际竞赛项目做出贡献。