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Non equilibrium transport and dynamics in conventional and topological superconducting junctions

常规和拓扑超导结中的非平衡输运和动力学

基本信息

批准号：
326061083
负责人：
Dr. Gianluca Rastelli, Ph.D.
金额：
--
依托单位：
Arbeitsgruppe Theorie des Quantentransports
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/326061083?language=en
关键词：
Non equilibrium transport dynamics conventional

项目摘要

This project concerns the theoretical study of quantum transport and non-equilibrium dynamics in superconducting junctions coupled to an electromagnetic environment and microwave irradiation, taking into account quasiparticle effects.Recent experiments have focused on superconducting junctions in various kinds of nanostructures (such as atomic contacts and topological materials) with the objective of creating a novel type of versatile superconducting junction beyond the standard Josephson tunnel junctions. These systems are promising for the potential realization of new types of qubits that are based on single Andreev levels with some envisioned protection against dissipation and decoherence. Indeed, junctions using topological materials are expected to give rise to special Andreev levels that correspond to Majorana states whose unambiguous detection is currently the subject of intense study.One important and common problem in mesoscopic superconducting junctions is the non-equilibrium population of long-lived quasiparticles. The underlying mechanisms for the relaxation dynamics and non-equilibrium properties of these quasiparticles are not fully understood. The presence of quasiparticle excitations degrades or even disrupts the operation of the systems, and thus such particles represent an intrinsic source of decoherence and dissipation. Understanding the non-equilibrium dynamics of quasiparticles is therefore a crucial issue.This project sets out to study the effects of quasiparticles in state-of-the-art novel superconducting junctions including atomic point contacts, short nanowires, and topological junctions. Specifically, motivated by recent results in Andreev spectroscopy experiments, this project will study the properties of junctions when they are irradiated by microwaves to reveal the Andreev excitation spectrum and its dynamics. For such systems, we will provide a theoretical framework for the non-equilbrium dynamics of the quasiparticles based on the interplay between the time-dependent external field and the fluctuations of the electromagnetic environment.Ongoing experiments in atomic junctions call for a theoretical analysis that includes all these aspects simultaneously. As this is theoretically challenging, this project represents pioneering work in the field.Understanding these effects is a crucial prerequisite for fully exploiting this new class of device in the form of novel, dissipation-free, non-linear elements in quantum circuits or in qubits architectures.Finally, the greatest innovation of the project is its extension of the theoretical investigation to include topological junctions. Anticipating future experiments, the project aims at a major breakthrough by analyzing a theoretical proposal to experimentally reveal Majorana states using Andreev spectroscopic measurementsin topological superconducting junctions.

本计画系关于超导接面在电磁环境及微波照射下之量子输运与非平衡动力学之理论研究，最近的实验主要集中在各种纳米结构中的超导结上（如原子接触和拓扑材料）其目的是创造一种超越标准约瑟夫森隧道结的新型通用超导结。这些系统有望实现基于单个Andreev能级的新型量子位，并具有一些预期的防止耗散和退相干的保护。事实上，使用拓扑材料的结预计会产生特殊的Andreev能级，对应于Majorana状态，其明确的检测是目前深入研究的主题。介观超导结中一个重要而常见的问题是长寿命准粒子的非平衡布居。这些准粒子的弛豫动力学和非平衡性质的基本机制还没有完全理解。准粒子激发的存在会降低甚至破坏系统的运行，因此这种粒子代表了退相干和耗散的内在来源。因此，了解准粒子的非平衡动力学是一个至关重要的问题。本项目旨在研究准粒子在最先进的新型超导结（包括原子点接触、短纳米线和拓扑结）中的作用。具体而言，受Andreev光谱实验的最新结果的启发，该项目将研究结在微波照射下的特性，以揭示Andreev激发光谱及其动力学。对于这样的系统，我们将提供一个理论框架的非平衡动力学的准粒子之间的相互作用的依赖于时间的外场和电磁环境的波动。正在进行的实验在原子结要求的理论分析，同时包括所有这些方面。由于这在理论上具有挑战性，该项目代表了该领域的开创性工作。理解这些效应是充分利用这种新型器件的关键先决条件，这种新型器件以量子电路或量子比特架构中的新颖，无耗散，非线性元件的形式存在。最后，该项目最大的创新是将理论研究扩展到包括拓扑结。预计未来的实验，该项目的目标是通过分析一个理论提案，在拓扑超导结中使用Andreev光谱测量实验揭示Majorana状态，从而实现重大突破。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Interplay between Yu-Shiba-Rusinov states and multiple Andreev reflections

DOI：
10.1103/physrevb.101.235445
发表时间：
2020-05
期刊：
Physical Review B
影响因子：
3.7
作者：
A. Villas;Raffael L. Klees;Haonan Huang;C. Ast;G. Rastelli;W. Belzig;J. Cuevas
通讯作者：
A. Villas;Raffael L. Klees;Haonan Huang;C. Ast;G. Rastelli;W. Belzig;J. Cuevas

Nonequilibrium Andreev bound states population in short superconducting junctions coupled to a resonator

与谐振器耦合的短超导结中的非平衡安德烈夫束缚态布居