Characterising and Optimising the Microwave Properties of Nanobridge Josephson Junctions

1.有限元模拟模拟不同功率和温度下的约瑟夫森结和SQUID的微波效应利用MDLSI为不同的环尺寸和锐度模拟带有纳米桥结的纳米SQUID的有效电感1)自旋相对于SQUID的位置与SQUID环的位置有关的自旋探测灵敏度2)SQUIDs环和z方向自旋之间的距离2)制备和实验装置进一步发展薄膜器件的制备方法，包括注入自旋团簇的积分。这涉及到结制造技术的选择、低温恒温器内芯片的热控制。这些设备的特点将是一系列的显微镜(原子力显微镜、扫描电子显微镜等)开发闭合循环冷却器系统，以整合SQUID系列阵列，并将读出电子设备与闭合循环冷冻恒温器集成在一起。使用SolidWorks进行机械设计和布局，包括偏置T、环行器、低噪声微波放大器和分接盒。系列SQUID阵列读取器基于纳米桥结的纳米SQUID将被测试并针对包括操作温度、噪声性能和磁场操作在内的多个参数进行优化。微波响应性能将被测量并与所产生的建模结果相比较(第二章)。GA FIB和He-Ne FIB器件的性能将被评估和优化(可能的论文)纳米SQUID与SSA读出系统的集成将提供进一步的发展途径。纳米SQUID系统的噪声性能将被评估，从而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，需要增加读出带宽和探测系统的灵敏度。这将通过实施微波感应读出方案，结合利用微波脉冲序列对自旋进行势能操纵来实现。将低温低噪声放大器和其他微波组件集成到闭合循环冷却器系统中。测试微波探测方法的性能，从温度、磁场和微波功率参数方面进行测试。5.自旋簇检测为了进一步开发系统，将使用SSA系统测量一系列以前以常规读出为特征的自旋簇鱿鱼芯片。进一步的优化应该可以通过将相同的芯片与微波感应读出系统相集成来实现。两种检测方案的操作参数空间(温度、磁场)

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