权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

New architectures for topological superconductors

拓扑超导体的新架构

基本信息

批准号：
EP/V048678/1
负责人：
Gunnar Moeller
金额：
$ 25.79万
依托单位：
University of Kent
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2021
资助国家：
英国
起止时间：
2021 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FV048678%2F1
关键词：
New architectures topological superconductors

项目摘要

This proposal aims to explore a new platform for creating topological superconducting states of matter.During the last decade, concepts of topology have evolved into a central aspect of the study of materials, with foundations of these ideas relating to the study of thin sheets of superconductors or conductors in strong magnetic fields, as recognised in the 2016 Nobel Prize for topological phase transitions and topological phases of matter. Topology deals with classifying properties of geometrical objects that remain unchanged when the object is smoothly reshaped. For example, one can smoothly mould a coffee cup into a doughnut, so these objects have the same topology, characterised by a single hole piercing these bodies.Similarly, in materials science, the topology of quantum states of matter relates to the type of properties that remain constant even when some aspects of the material are changed. The quantum Hall effect, measured when a thin two-dimensional conductor is placed into strong magnetic fields, is a good example in that the resulting Hall resistance is universal, i.e. it is the same for all materials (at the same density of charge), independently of their chemical structure or purity. In other words, topological phases actually require a large external influence to be applied before they display an actual change in behaviour. This stability leads to attraction of topological matter as a platform for storing and processing quantum information: the challenge for building robust quantum-computers is precisely to control quantum information and shield it from the influence of the environment. While current-day quantum computers start to produce first results that would be difficult to obtain on classical machines, they can only process information for a short amount of time before most of the initial information is lost. This means that these computers can only run algorithms that are sufficiently short, hence limiting their usefulness. Replacing their current hardware of superconducting flux qubits with Majorana degrees of freedom in topological superconductors could be a possible route to eliminate excessive loss of information and enable highly performing quantum computers.It is already known how topological superconductors can be created in sandwich structures made of conventional superconductors and materials with spin-orbit coupling. These systems form the basis for the technology of Majorana wires, one dimensional topological superconductors which are thought to carry Majorana fermion states at their ends, exotic quantum states that benefit from topological protection. In these systems, the spin-orbit coupling is inherent to the materials used, which is generally tied to heavy elements, and there is limited control of its magnitude or characteristics.Here, we propose to theoretically study a new type of heterostructures built from a layer of ordinary superconductors combined with an engineered layer in which an effective spin-orbit coupling can be engineered at a local level. Building on insights of how synthetic gauge fields or effective gravitational metrics can be created from a range of different physical mechanisms, we will create a theoretical model for a promising platform to realise synthetic spin-orbit couplings which can be conveniently manipulated with electric fields. We expect that coupling such materials to ordinary superconductors can provide fine-grained control to target specific topological superconducting states. Additionally, given the ability to create more complex spatial patterns of effective spin-orbit coupling in these systems, we will explore whether this local control could be exploited to build new types of quantum devices for quantum information processing.Finally, our systems can also be regarded as analogues of gravitational fields, so we will consider them from this angle and explore connections with astrophysical settings.

在过去的十年中，拓扑学的概念已经发展成为材料研究的一个核心方面，这些概念的基础与超导体薄片或强磁场中导体的研究有关，这一点在2016年诺贝尔物理学奖的拓扑相变和拓扑相中得到了认可。拓扑处理几何对象的分类属性，这些属性在对象平滑重塑时保持不变。例如，人们可以将一个咖啡杯平滑地塑造成一个甜甜圈，因此这些物体具有相同的拓扑结构，其特征在于这些物体上都有一个孔。同样，在材料科学中，物质的量子态拓扑结构与即使材料的某些方面发生变化也保持不变的性质类型有关。量子霍尔效应是一个很好的例子，当一个薄的二维导体被放置在强磁场中时，所产生的霍尔电阻是通用的，即它对所有材料都是相同的（在相同的电荷密度下），与它们的化学结构或纯度无关。换句话说，拓扑阶段实际上需要施加很大的外部影响，然后才能显示实际的行为变化。这种稳定性吸引了拓扑物质作为存储和处理量子信息的平台：构建强大的量子计算机的挑战正是控制量子信息并使其免受环境影响。虽然目前的量子计算机开始产生在经典机器上难以获得的第一个结果，但它们只能在大部分初始信息丢失之前处理短时间的信息。这意味着这些计算机只能运行足够短的算法，从而限制了它们的实用性。用拓扑超导体中的马约拉纳自由度取代当前的超导通量量子比特硬件，可能是消除信息过度丢失并实现高性能量子计算机的一种可能途径。人们已经知道如何在由传统超导体和具有自旋轨道耦合的材料制成的三明治结构中创建拓扑超导体。这些系统形成了马约拉纳线技术的基础，马约拉纳线是一维拓扑超导体，被认为在其末端携带马约拉纳费米子态，这种奇异的量子态受益于拓扑保护。在这些系统中，自旋-轨道耦合是固有的材料，这通常是绑定到重元素，并有有限的控制其大小或characteristics.Here，我们建议从理论上研究一种新型的异质结构，从一层普通的超导体与工程层相结合，其中一个有效的自旋-轨道耦合可以在局部水平上设计。基于如何从一系列不同的物理机制中创建合成规范场或有效引力度量的见解，我们将创建一个有前途的平台的理论模型，以实现可以方便地用电场操纵的合成自旋轨道耦合。我们希望将这种材料与普通超导体耦合可以提供针对特定拓扑超导状态的细粒度控制。此外，考虑到在这些系统中能够产生更复杂的有效自旋轨道耦合空间模式，我们将探索是否可以利用这种局部控制来构建用于量子信息处理的新型量子设备。最后，我们的系统也可以被视为引力场的类似物，因此我们将从这个角度考虑它们，并探索与天体物理环境的联系。