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/E026532/1
• 负责人: Mark Blamire
• 金额: $ 38.53万
• 依托单位: University of Cambridge
• 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%2FE026532%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 pi 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.

关于电子电路的发展，国际活动正在迅速扩展，可以用作人工原子，因为它们具有一组明确定义的量子状态。此类电路被称为量子位（Qubits），其应用范围从量子计算到测量标准。这些量子状态极为脆弱（很容易挑战），最容易在非常低的温度（<1k）下建立，并且可以通过环境中的电子噪声来源或与材料本身相关的来破坏。事实证明，超导材料对于量子的制造非常成功，并且进步迅速，近年来，基于超导循环中约瑟夫森连接的多种方法正在证明，具有显着提高免疫力的QUITIND对该领域极为重要。基于非常规Josephson设备（称为PI连接）的非常规的Qubits有许多设计。其中有两种主要类型：超导隧道连接连接，它们在隧道屏障和一个电极（SFIS结构）之间包含铁磁层，以及带有常规超导体的连接器作为一个电极和D-Wave超导管作为另一个电极（SND结构）。该提案的目的是进行关键实验，以测试其对量子应用的适用性。这两个系统具有许多常见的特征，因此通过并行研究，我们将能够采用常见的实验方法，评估它们的相对优点和差异，并确定依赖于PI连接的Qubit设计的总体可行性。 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从金属和氧化物异质结构和高于1K的温度下进行测量的超导装置的制造，因此，它们在该区域的重大影响都很好。

项目成果

0-p oscillations in nanostructured Nb/Fe/Nb Josephson junctions

纳米结构 Nb/Fe/Nb 约瑟夫森结中的 0-p 振荡

• DOI: 10.1140/epjb/e2007-00210-8
• 发表时间: 2007
• 期刊: The European Physical Journal B
• 作者: Piano S