Novel collective phenomena in Majorana fermion devices

许多粒子的集体行为经常产生一些现象，这些现象违背了人们基于控制系统的微观规则的直觉。一个引人注目的例子是新的奇异粒子的出现，它们的性质与单个组成部分完全不同。这是最近最令人兴奋的发现之一，马约拉纳费米子，这种奇异粒子，可以出现在某些超导体结构中。与超导体的电子不同，马约拉纳费米子是中性的，以量子力学的非局域方式隐藏电荷。对这些粒子的兴奋，超出了它们的基础科学，是由于在量子计算应用中利用这种固有量子非局域性的前景。设计容纳马约拉纳费米子0D（从所有方向限制）和1D（沿着一个方向延伸）形式的系统的实验工作正在进行中，最近报道了第一个有希望的特征。在这些发展的推动下，理论研究的主要目标之一是设计新的方法和设备来探测和操纵马约拉纳费米子。本理论研究旨在基于马约拉纳费米子不仅可以产生，还可以参与甚至引起新的集体量子现象的观察，探索研究马约拉纳费米子的新途径。聚焦于这些由空间局域（“杂质”）性质的强相互作用促进的情况，该研究将探索(1)当传导电子耦合到带有0D马约拉纳费米子的设备时，(2)在带有1D马约拉纳费米子的设备中产生的新的许多粒子物理。科学目标是：揭示和描述（例如，通过散射特性、空间和其他组织模式）集体行为的基本新形式；并预测实验观察到的现象，这些现象可以作为对马约拉纳费米子特征（如非定域性）的深入测试，并可能影响旨在操纵马约拉纳费米子的设备的行为。拟议的工作，除了与正在进行的马约拉纳费米子研究直接相关外，还有可能为马约拉纳费米子和强相互作用系统的研究团体之间的交叉受精提供新的途径。

The collective behaviour of many particles often gives rise to phenomena defying one's intuition based on the microscopic rules governing the system. A striking example is that of the emergence of new, exotic particles, with properties completely different from those of the individual constituents. It is one of the most exciting recent discoveries that Majorana fermions, exotic particles of this kind, can emerge in certain superconductor structures. Majorana fermions, unlike the superconductor's electrons, are neutral, concealing the electric charge in a quantum mechanical, nonlocal manner. The excitement about these particles, beyond their fundamental science, is due to the prospects of taking advantage of this intrinsic quantum nonlocality in quantum computing applications.Experimental work on systems designed to host 0D (confined from all directions) and 1D (extending along one direction) forms of Majorana fermions is ongoing, with the first promising signatures reported recently. Among the main goals of theoretical research motivated by these developments is to devise new methods and devices for detecting and manipulating Majorana fermions. This theoretical research aims at exploring a novel avenue for studying Majorana fermions based on the observation that they can not only result, but also participate in, or even cause novel collective quantum phenomena. Focusing on the case where these are promoted by strong interactions of spatially localised ("impurity") nature, the research will explore new many particle physics arising (1) when conduction electrons are coupled to devices with 0D Majorana fermions and (2) in devices hosting 1D Majorana fermions. The scientific goals are: to uncover and describe (e.g., via scattering properties, spatial and other organisation patterns) fundamentally new forms of collective behaviour; and to predict experimentally observable phenomena that can serve as in-depth tests of Majorana fermion features (such as nonlocality) and can influence the behaviour of devices aimed at Majorana fermion manipulation. The proposed work, in addition to being directly relevant to ongoing Majorana fermion research, has the potential to provide new routes for cross-fertilisation between the communities working on Majorana fermions and strongly interacting systems.