Collaborative Research: Kinetic Inductance in Superconducting Nanowire Microwave Devices

提案标题：合作研究：超导纳米线微波器件中的动力学电感超导纳米线可以具有比它们的磁电感大几个数量级的动力学电感。结果，纳米线上的高频信号经历显著的空间压缩以及它们的速度的显著降低。动态电感也作为电流的函数非线性地变化，从而创造了以极小的耗散实现非线性现象的机会。通过理论，建模和实验相结合，该项目将研究这些影响在不同的超导纳米线材料和几何形状。从这些研究中获得的理解将被应用于设计新型的超紧凑微波器件，然后将被制造和表征。这些设备可以作为开发基于超导电路的更复杂系统的重要组成部分，如单光子成像器和量子计算机。该合作项目汇集了马萨诸塞州理工学院和北佛罗里达大学（一所以本科教育为重点的大学）的团队，以开展拟议的研究和教育活动，结合两个机构的最佳方面。特别是，北佛罗里达大学的参与为来自不同背景的本科生创造了额外的机会参与研究。技术摘要本项目的目标是建立一个新的超导纳米线器件平台，可以作为单片超导纳米线微波集成电路技术的基础。这一目标将通过四种办法来实现。第一种方法是基于探索材料和几何形状，最大限度地提高纳米线的动力学感应率，这将导致非常大的特性阻抗（10千欧）沿着缓慢的信号速度和信号波长的大空间压缩。如此高的阻抗产生了与环境的强解耦，并具有从超导纳米线单光子探测器的读出到量子比特设计的潜在应用。第二种方法将是在极高介电常数的衬底上制造纳米线，例如钛酸锶，其已被证明在低温下具有高达10，000的相对介电常数。这种极大的介电常数将显著提高电容，使高电感纳米线的特性阻抗接近50 kohm，同时实现超慢信号速度和超压缩信号波长。50 kohm阻抗对于与常规微波电路耦合至关重要。第三种方法将侧重于理解和利用动力学电感的非线性电流依赖性，以创建新型的基于MEMS的非线性微波器件。此类装置的实例包含混频器、可调谐耦合器、开关及参数放大器。为了理解这些器件，该项目将寻求解决基本问题，例如纳米线的动力学电感可以多快地被调制，与这种调制相关的损耗有多大，以及非线性和损耗如何取决于信号功率。第四种方法将利用前三种方法产生的结果来开发更复杂的基于MEMS的器件和电路。该奖项反映了NSF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。

Proposal Title:Collaborative Research: Kinetic Inductance in Superconducting Nanowire Microwave DevicesNon-Technical AbstractSuperconducting nanowires can have a kinetic inductance that is several orders of magnitude larger than their magnetic inductance. As a result, high frequency signals on the nanowire experience significant spatial compression as well as a significant reduction in their velocity. The kinetic inductance also varies nonlinearly as a function of the current, creating an opportunity for realizing nonlinear phenomena with extremely minimal dissipation. Through a combination of theory, modeling, and experiment, this project will study these effects in different superconducting nanowire materials and geometries. The understanding gained from these studies will be applied to design new types of ultra-compact microwave devices, which will then be fabricated and characterized. Such devices can serve as important building blocks for the development of more complex systems based on superconducting circuits such as single-photon imagers and quantum computers. This collaborative project brings together groups at Massachusetts Institute of Technology and the University of North Florida, an undergraduate-education focused university, to conduct the proposed research and educational activities, combining the best aspects of both institutions. In particular, the involvement of the University of North Florida creates additional opportunities for undergraduates from diverse backgrounds to participate in the research.Technical AbstractThe goal of this project is to create a new superconducting nanowire device platform that can serve as the basis of a monolithic superconducting nanowire microwave integrated circuit technology. This goal will be pursued through four approaches. The first approach is based on exploring materials and geometries that maximize the nanowire's kinetic inductivity, which will result in extremely large characteristic impedances ( 10 kohm) along with slow signal velocities and large spatial compression of the signal wavelengths. Such high impedances create strong decoupling from the environment and have potential applications ranging from the readout of superconducting nanowire single-photon detectors to the design of quantum bits. The second approach will be to fabricate nanowires on extremely high permittivity substrates such as strontium titanate, which has been shown to have a relative permittivity as high as 10,000 at low temperature. This extremely large permittivity will significantly boost the capacitance, bringing the characteristic impedance of high-inductance nanowires close to 50 kohm while simultaneously achieving ultra-slow signal velocities and ultra-compressed signal wavelengths. A 50 kohm impedance is critical to coupling with conventional microwave circuitry. The third approach will focus on understanding and exploiting the nonlinear current-dependence of kinetic inductance in order to create new types of nanowire-based nonlinear microwave devices. Examples of such devices include mixers, tunable couplers, switches, and parametric amplifiers. In order to understand these devices, the project will seek to address fundamental questions such as how quickly the nanowire's kinetic inductance can be modulated, how much loss is associated with this modulation, and how the nonlinearity and the loss depend on the signal power. The fourth approach will leverage the results generated in the first three approaches to develop more complex nanowire-based devices and circuits.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.