Broadband Quantum limited Traveling-Wave Parametric Amplifier based on a Superconducting Metamaterial Transmission Line

题目：基于超导超材料传输线的宽带量子受限行波参量放大器技术描述：利用量子受限放大器探测微弱微波信号的研究重新燃起了人们的兴趣。这种放大器允许在射电天文学中进行超灵敏探测（如暗物质搜索或宇宙微波背景研究），具有光子数分辨率的探测器，超安全量子通信以及超导量子比特的实时监控。低电平信号的检测，特别是在单光子水平是具有挑战性的，其中放大器的噪声水平受到量子力学波动的限制，需要一个令人满意的信噪比测量。在这个项目中，一种新型的行波参数放大器（TWPA）由可调谐的超材料传输线组成，它将允许在微波条件下利用低损耗超导电路在宽带宽上对弱信号进行有效的参数放大。构成所提出放大器的超材料传输线可以被调谐为具有负折射率，从而允许在非常短的长度内有效放大，这有助于减少噪声并促进可扩展性。参与这项研究的学生将接触到现代固态科学与工程中最先进的实验技术，并将能够通过参加面向K-12学生和教师的推广活动来分享他们对科学和工程的热情。外联活动包括将移动原子力显微镜示范实验室带到K-12学校。演示纳米科学概念。技术描述：目前最先进的TWPA设计主要基于约瑟夫森结的系列阵列，最初是在20世纪80年代初引入的。这些设计的局限性阻碍了它们的广泛使用和采用。这些限制与相位匹配、弱非线性和超过量子极限数倍的过量噪声有关。在本研究项目中，我们建议采用一种完全不同的方法来进行TWPA的相位匹配。所提出的TWPA由一条超材料传输线组成，该传输线将允许在微波条件下利用低损耗超导电路在宽带宽上进行有效的参数放大。超材料传输线由独特的磁阻耦合非对称超导量子干涉器件网络组成。所提出的超材料传输线的折射率（阻抗）的可调性允许将折射率的非线性分量从正调谐到负，从而可以将弱信号与强泵相匹配，并导致弱信号的有效参数放大。拟议的TWPA预计将在宽带宽（5 GHz）上提供高增益（20 dB），同时保持噪声性能的量子限制。本研究的目标是：(1)制作TWPA原型；(2)表征TWPA的增益、带宽、动态范围和附加噪声；(3)验证TWPA噪声性质的量子限制；(4)研究TWPA在参数变化下的性能；(4)研究TWPA中导致过度噪声的损耗机制。

Title: Broadband Quantum Limited Traveling-Wave Parametric Amplifier based on a Superconducting Metamaterial Transmission LineNon-Technical Description:There has been renewed interest in utilizing quantum limited amplifiers for detection of weak microwave signals. Such amplifiers have allowed for ultra-sensitive detection in radio astronomy (such as dark matter searches or cosmic microwave background studies), detectors with photon number resolution, ultra-secure quantum communications, and real time monitoring of superconducting quantum bits. Detection of low level signals, particularly at the single photon level is challenging, where amplifiers which have noise levels which are limited by quantum mechanical fluctuations are required for a satisfactory signal-to-noise ratio measurement. In this project a novel traveling-wave parametric amplifier (TWPA) composed of a tunable metamaterial transmission line which will allow for efficient parametric amplification of a weak signal over a broad bandwidth in the microwave regime utilizing low-loss superconducting circuits is developed. The metamaterial transmission line which makes up the proposed amplifier can be tuned to have a negative refractive index which allows for efficient amplification over very short lengths, which aides in the reduction of noise and promotes scalability. Students participating in this research will be exposed to state-of-the-art experimental techniques in modern solid-state science and engineering, and will also be able to share their enthusiasm for science and engineering by participating in outreach activities to K-12 students and teachers. Outreach activities include mobile atomic force microscope demonstrative laboratory which are brought to K-12 institutions.to demonstrate nanoscience concepts.Technical Description:Present state-of-the-art TWPA designs have been primarily based on series arrays of Josephson junctions as originally introduced in the early 1980s. Limitations in these designs have prevented their wide-spread use and adoption. These limitations have to do with: phase matching, weak nonlinearities, and excessive noise several times the quantum limit. In this research program we propose to take an entirely different approach to phase matching in a TWPA. The proposed TWPA is composed of a metamaterial transmission line which will allow for efficient parametric amplification over a broad bandwidth in the microwave regime utilizing low-loss superconducting circuits. The metamaterial transmission line is composed of a unique network of coupled magnetically frustrated asymmetric superconducting quantum interference devices. The tunability of the refractive index (impedance) of the proposed metamaterial transmission line in situ allows for the nonlinear component of the refractive index to be tuned from positive to negative which can phase match a weak signal to a strong pump and result in efficient parametric amplification of the weak signal. The proposed TWPA is expected to deliver high gain ( 20 dB) over a broad bandwidth ( 5 GHz) while maintaining quantum limited in noise performance. The objectives of the proposed research are: (1) to fabricate prototype TWPAs (2) Characterize the gain, bandwidth, dynamic range, and added noise (3) Validate the quantum limited in noise nature of the TWPA (4) Investigate the performance of the TWPA in the presence of parameter variations (4) Study loss mechanisms in the TWPA which contribute to excessive noise.