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非技术摘要超导纳米线的动力学电感可以比它们的磁电感大几个数量级。结果，纳米线上的高频信号经历了显著的空间压缩，其速度也显著降低。动力学电感也作为电流的函数非线性变化，为以极小的损耗实现非线性现象创造了机会。通过理论、模型和实验的结合，本项目将研究不同超导纳米线材料和几何形状的这些效应。从这些研究中获得的认识将被用于设计新型的超紧凑型微波器件，然后将其制造和表征。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，如单光子成像仪和量子计算机。这个合作项目汇集了麻省理工学院和北佛罗里达大学的团队，这是一所专注于本科教育的大学，以开展拟议的研究和教育活动，结合了两所机构的最佳方面。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更多参与研究的机会。技术摘要该项目的目标是创建一个新的超导纳米线设备平台，该平台可以作为单片超导纳米线微波集成电路技术的基础。这一目标将通过四个途径来实现。第一种方法是基于最大限度地提高纳米线的动力学感应性的材料和几何结构，这将导致极大的特征阻抗(10Kohm)，以及缓慢的信号速度和巨大的信号波长空间压缩。这种高阻抗产生了与环境的强烈去耦合，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。第二种方法是在极高的介电常数衬底上制备纳米线，如钛酸锶，它在低温下的相对介电常数高达10,000。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征阻抗接近50Kohm，同时实现超慢信号速度和超压缩信号波长。50Kohm阻抗是与传统微波电路耦合的关键。第三种方法将专注于理解和利用动力学电感的非线性电流依赖关系，以创造新型的基于纳米线的非线性微波器件。这类器件的例子包括混频器、可调耦合器、开关和参数放大器。为了了解这些设备，该项目将寻求解决基本问题，如纳米线的动态电感可以多快被调制，这种调制有多大的损耗，以及非线性和损耗如何依赖于信号功率。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纳米线的设备和电路。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.