The quantum dynamics of Josephson junctions with controlled current-phase relationships

具有受控电流相位关系的约瑟夫森结的量子动力学

• 批准号: EP/E026494/1
• 负责人: Edward Tarte
• 金额: $ 51.16万
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FE026494%2F1
• 关键词: quantum; dynamics; Josephson; junctions; controlled

There is rapidly expanding international activity on the development of electronic circuits which can be used as artificial atoms in that they possess a set of well defined quantum states. Such circuits are known as quantum bits (qubits) with applications ranging from quantum computing to measurement standards. These quantum states are extremely fragile (decohere readily), are most easily established at very low temperatures (<1K) and can be destroyed by sources of electronic noise in the environment or associated with the materials themselves. Superconducting materials have proved to be very sucessful for qubit fabrication and progress has been rapid with a number of approaches being demonstrated in recent years based upon Josephson junctions in superconducting loops.Qubit designs with significantly improved immunity to decoherence would extremely important to this field. There have been a number of designs for environmentally decoupled qubits based upon unconventional Josephson devices known as pi junctions. There are two main types of these: superconducting tunnel junctions which contain a ferromagnetic layer between the tunnel barrier and one electrode (SFIS structures) and junctions with a conventional superconductor as one electrode and a d-wave superconductor as the other (SND structures). The aim of this proposal is to carry out the key experiments which test their suitability for qubit applications. The two systems share many features common and so by investigating both in parallel, we will be able employ common experimental approaches, evaluate their relative merits and differences and to determine the overall feasibility of qubit designs which rely on ? junctions. The experiments will involve optimising both technologies for qubit applications, determining what junction designs give the most suitable pi junction behaviour, investigating potential intrinsic noise sources associated with the devices, investigating whether the junctions themselves develop well defined quantum states at low temperature and finally, using the results of the previous experiments to select a suitable qubit design and investigate its properties.The applicants are researchers at the Universities of Cambridge and Birmingham with a strong track record of the fabrication of superconducting devices from metallic and oxide heterostructures and measurements at temperatures below 1K, who are thus well placed to make a major impact in this area.

国际上正在迅速扩大开发电子电路的活动，这些电路可以用作人造原子，因为它们具有一组定义明确的量子态。这种电路被称为量子比特（qubit），其应用范围从量子计算到测量标准。这些量子态非常脆弱（容易退相干），在非常低的温度（<1K）下最容易建立，并且可以被环境中的电子噪声源或与材料本身相关的电子噪声源破坏。近年来，基于超导回路中的约瑟夫森结的量子比特制备方法得到了迅速的发展，具有显著抗退相干性的量子比特设计对该领域具有重要意义。已经有许多基于称为π结的非常规约瑟夫森器件的环境解耦量子位的设计。这些主要有两种类型：超导隧道结，其中包含隧道势垒和一个电极之间的铁磁层（SFIS结构）和传统超导体作为一个电极和d波超导体作为另一个电极的结（SND结构）。该提案的目的是进行关键实验，以测试它们对量子比特应用的适用性。这两个系统有许多共同的特点，因此通过并行研究，我们将能够采用共同的实验方法，评估它们的相对优点和差异，并确定量子位设计的总体可行性，这些设计依赖于？交叉点实验将涉及优化量子比特应用的两种技术，确定什么样的结设计给出最合适的π结行为，调查与设备相关的潜在固有噪声源，调查结本身是否在低温下发展出定义良好的量子态，最后，利用先前实验的结果来选择合适的量子比特设计并研究其性质。申请人是剑桥大学和伯明翰大学的研究人员，在从金属和氧化物异质结构制造超导器件以及在低于1K的温度下进行测量方面有着良好的记录，因此他们很有可能在这一领域产生重大影响。

项目成果

New Multilayer Architectures for Piezoelectric BaTiO 3 Cantilever Systems

用于压电 BaTiO 3 悬臂系统的新型多层架构

• DOI: 10.1557/opl.2011.970
• 发表时间: 2011
• 期刊: MRS Proceedings
• 作者: Vasta G