Characterising and Optimising the Microwave Properties of Nanobridge Josephson Junctions

表征和优化纳米桥约瑟夫森结的微波特性

• 批准号: 1992306
• 金额: --
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1992306
• 关键词: Characterising; Optimising; Microwave; Properties; Nanobridge

1. Finite Element ModellingModel the microwave effect on Josephson junctions and SQUIDs with different powers and temperaturesModel the effective inductance of nanoSQUIDs with nanobridge junctions using MDLSI for different loop size and sharpModel the spin detection sensitivity as a function of the position of the spin relative to SQUID1) Position related to SQUIDs loop2) Distance between the SQUIDs loop and spin in z direction2.Fabrication and Experimental SetupFurther development of thin film device fabrication methods, including integration of implanted spin clusters. This involves selection of techniques of junction fabrication, thermal control of chips within cryostat. The devices will be characterised by a range of microscopies (AFM, SEM, etc.)Develop closed cycle cooler system to incorporate SQUID Series Array and integrate readout electronics with the closed-cycle cryostat.Mechanical design and layout using SolidWorks to include Bias T, Circulator, Low Noise Microwave Amplifier and break-out box.3. Series SQUID Array ReadoutNanobridge junction based nanoSQUIDs will be tested and optimised with respect to anumber of parameters including temperature of operation, noise performance and magneticfield operation.Microwave response performance will be measured and compared with the modelling resultsproduced (Chapter 2).Ga FIB and He-Ne FIB device performance will be assessed and optimised (possible paper)Integration of nanoSQUIDs with the SSA readout system will provide a further developmentpath.Noise performance of the nanoSQUID systems will be evaluated, leading to predictions ofspin sensitivity.4.Inductive Microwave ReadoutTo optimise future applications of nanoSQUIDs for quantum technologies it is desirable toincrease the readout bandwidth and sensitivity of the detection system. This will beachieved by implementation of a microwave inductive readout scheme, coupled with apotential manipulation of spins with microwave pulse trains.Integration of cryogenic low-noise amplifier and other microwave components to closedcycle cooler system.Test performance of microwave detection method, in terms of temperature, magnetic fieldand microwave power parameters.5.Spin Cluster DetectionIn order to further develop the system, a range of spin cluster SQUID chips, previouslycharacterised with conventional readout, will be measured with the SSA system.Further optimisation should be possible by integration of the same chips with the microwaveinductive readout system.Operational parameter space (temperature, magnetic field) for both detection schemes

1.有限元建模模拟不同功率和温度下约瑟夫森结和SQUID上的微波效应使用MDLSI针对不同环路尺寸和锐度模拟具有纳米桥结的纳米SQUID的有效电感将自旋检测灵敏度建模为自旋相对于SQUID的位置的函数1）与SQUID环路相关的位置2）SQUID环和自旋之间的距离在z方向2.制造和实验设置薄膜器件制造方法的进一步发展，包括注入自旋团簇的集成。这涉及到结制造技术的选择，低温恒温器内芯片的热控制。将通过一系列显微镜（AFM、SEM等）对器械进行表征。开发封闭循环冷却器系统，以整合SQUID系列阵列，并将读出电子设备与封闭循环低温恒温器集成。使用SolidWorks进行机械设计和布局，包括偏置T，循环器，低噪声微波放大器和接线盒。系列SQUID阵列读出基于纳米桥结的纳米SQUID将在许多参数方面进行测试和优化，包括工作温度，噪声性能和磁场操作。微波响应性能将被测量，并与模拟结果进行比较（第二章）.Ga FIB和He-Ne FIB器件性能将被评估和优化（可能的论文）将nanoSQUID与SSA读出系统集成将提供进一步的发展途径。将评估nanoSQUID系统的噪声性能，导致自旋灵敏度的预测。4.感应微波读出为了优化纳米SQUID在量子技术中的未来应用，需要增加读出带宽，检测系统的灵敏度。这将通过实施微波感应读出方案，再加上用微波脉冲序列对自旋进行潜在操纵来实现。将低温低噪声放大器和其他微波部件集成到闭合循环冷却器系统中。测试微波探测方法在温度、磁场和微波功率参数方面的性能。5.自旋团簇探测为了进一步开发该系统，一系列自旋团簇SQUID芯片，以前用常规读出表征，将用SSA系统测量。通过将相同的芯片与微波感应读出系统集成，进一步优化应该是可能的。两种检测方案的操作参数空间（温度，磁场）