Development of innovative superconducting electronics for multiplexing quantum sensors arrays

一种能够探测红外（IR）波长范围内的单光子，并具有准确的定时和空间信息的传感器，是一种至关重要的组件，将开启通信、医疗保健、环境监测和国防等战略部门的应用。这一关键技术支撑了安全信息的传输（量子通信/密码学），为下一代计算机（量子计算）的速度和计算能力的显著提高开辟了道路，并使成像和遥感技术（用于环境监测或成像的激光雷达、深空远程通信、用于癌症治疗的光动力疗法）的性能得到了巨大改善。基于半导体的红外光子计数器技术仍然不足以在21世纪最苛刻的应用中发挥重要作用。超导纳米线单光子探测器（SNSPDs）在探测1550nm波长的单红外光子时具有前所未有的性能，但仅限于15x15微米平方面积的单像素。大面积的snspd阵列将实现最终的单光子灵敏度和高时间分辨率，以及成像能力。将snspd扩展到大型焦平面阵列的主要挑战来自其在低温下的操作，并且需要特别注意设计有效的信号读出。本博士项目的目标是开发用于大型snspd阵列多路复用的超导电子读出方案。该电路将实现精确的时间戳、光谱分辨率和光子数信息的提取。与英国国家物理实验室（NPL）合作，我们正在探索一种基于超导纳米桥的单通量量子（SFQ）电路的读出方法，而不是传统的约瑟夫森结技术。在这种方法中，将单个光子吸收事件转换为单个通量量子，并通过低温超导电路进行处理。本项目将研究一系列用于多像素读出的新型纳米电桥SFQ读出器件。我们的最终目标是首次将片上读出与单电子束光刻步骤图案化的snspd结合起来。这将在现有的光子学平台上提供简单的制造，与量子技术直接集成，对单个电路组件的高控制，以及为特定应用量身定制传感器性能的灵活性。该项目将包括电路模拟，先进的纳米制造（在格拉斯哥大学詹姆斯瓦特纳米制造中心JWNC使用最先进的电子束光刻设备进行）。器件测试将主要在国家物理实验室的低温射频电气和光学表征设备上进行，博士生将在那里花费至少1年的时间。该项目完全符合QuantIC的目标，英国量子技术中心在量子增强成像（WP4超导探测器），并与当前创新英国量子技术可行性研究资助(集成超导纳米桥快速读出电子器件，用于单光子探测器阵列，由简爱尔兰博士在国家物理实验室领导。国家物理实验室强烈支持这个项目，并渴望加强与QuantIC和JWNC的联系；工业学生是实现这一目标的理想机制。目前的提案与EPSRC在以下繁荣成果驱动下的交付计划方面的目标产生了强烈的共鸣：开发和部署致力于以安全和值得信赖的方式连接人们的变革性技术；提高预测、诊断和治疗疾病的能力；发展世界领先的信息、计算机和工程技术。

A sensor capable of detecting single photons in the infrared (IR) wavelength range, with accurate timing and spatial information, is a crucial component that will unlock applications across strategic sectors such as communication, healthcare, environmental monitoring and defence. This key technology underpins for example the transfer of secure information (Quantum communication/cryptography), opens the path to dramatic enhancements in the speed and computational power of next generation computers (Quantum computing) and enables tremendous performance improvements in imaging and remote sensing techniques (LIDAR for environmental monitoring or imaging, deep space long distance communication, photodynamic therapy for cancer treatment). The semiconductor based IR photon counters technology is still not adequate to play a significant role in the most demanding 21st Century aforementioned applications. Superconducting nanowire single photon detectors (SNSPDs) can offer unprecedented performance when detecting single infrared photon at 1550 nm wavelength but are limited to single pixels of 15x15 micrometer square area. A large area array of SNSPDs will achieve the ultimate single-photon sensitivity and high temporal resolution, together with imaging capability. A major challenge in scaling up SNSPDs to large focal plane arrays arises from their operation at cryogenic temperatures and special care is needed in designing efficient signal readout. The goal of this PhD project is the development of superconducting electronic readout scheme for the multiplexing of a large arrays of SNSPDs. This circuit will enable precision time stamping, spectral resolution and extraction of photon number information. In partnership with the UK National Physical Laboratory (NPL) we are exploring a readout method using single flux quantum (SFQ) circuits based on superconducting nanobridges instead of the traditional Josephson junction technology. In this approach, a single photon absorption event is converted into a single flux quantum that is processed via a superconducting circuit at low temperature. This project will investigate a range of novel nanobridge SFQ readout devices for multi-pixel readout. Our eventual goal is to combine for the first time the readout on-chip with the SNSPDs patterned by a single electron beam lithography step. This will offer easy fabrication on existing photonics platforms for straightforward integration with quantum technologies, high control on the single circuitry components and flexibility in tailoring the performance of sensors for specific applications.This project will encompass circuit simulation, advanced nanofabrication (carried out using state-of-the-art electron beam lithography facilities in the James Watt Nanofabrication Centre JWNC at the University of Glasgow). Device testing will be mainly carried out using low temperature RF electrical and optical characterization facilities in laboratories at NPL where the PhD student will spend at least 1 year.This project is perfectly aligned with the goals of QuantIC, the UK Quantum Technology Hub in quantum enhanced imaging (WP4 Superconducting detectors), and with a current Innovate UK Quantum Technology Feasibility Study grant (Integrated superconducting nanobridge fast readout electronics for single photon detector arrays led by Dr Jane Ireland at the NPL. NPL strongly support this project and are keen to strengthen links with QuantIC and the JWNC; the industrial studentship is an ideal mechanism to enable this. The current proposal strongly resonates with the EPSRC's objectives in terms of delivery plan driven by the following prosperity outcomes: development and deployment of transformational technologies devoted to connect people in secure and trustworthy ways; improvement of the ability to predict, diagnose and treat disease; development of world-leading technology in information, computing and engineering.