Quantum dots with triplet and noncentrosymmetric superconducting leads

这个理论项目结合了当前凝聚态物理中的两个领域。其中之一涉及非传统超导体，特别是具有复杂磁性的所谓三重态和非中心对称超导体。它们具有不同寻常的表面态，即电子只能沿着表面运动，而不是进入本体。例如，可能存在大量这样的表面态，能量消失，建议形成所谓的Majorana费米子的固态实现。这些粒子形成了它们自己的反粒子。另一个相关领域是通过纳米分子或人造结构的电子传输。在这里，量子力学效应导致了与更大尺度上的传输截然不同的行为。这一领域对电子技术的进步也至关重要。本项目的目标是从理论上研究通过这种纳米结构在由三重态或非中心对称超导体制成的电极之间的传输。人们预计，一方面非传统超导体的物理学与通过纳米结构传输的量子效应之间的相互作用将导致新的物理学。例如，如果超导导线中存在许多Majorana态，它们将极大地改变电流-电压特性。这个项目的目标是发现和理解这些新的影响。为了实现这些目标，将使用适用于纳米结构和引线之间弱耦合和强耦合的补充理论方法。

Two fields of current interest in condensed matter physics are combined in this theoretical project. One of them concerns unconventional superconductors, in particular so-called triplet and noncentrosymmetric superconductors which have complex magnetic properties. They possess unusual surface states, i.e., states in which electrons can only move along the surface, not into the bulk. For example, there can be a large number of such surface states with vanishing energy, suggested to form a solid-state realization of so-called Majorana fermions. These are particles that form their own antiparticles. The other relevant field is electronic transport through nanometer-size molecules or artificial structures. Here, quantum-mechanical effects lead to behaviors quite distinct from transport at larger scales. This field is also crucial for technological progress in electronics. The objective of the present project is to theoretically study transport through such nanostructures between electrodes made from triplet or noncentrosymmetric superconductors. It is expected that the interplay between the physics of unconventional superconductors on the one hand and quantum effects in transport through nanostructures on the other will lead to novel physics. For example, if many Majorana states are present in the superconducting leads, they will dramatically change the current-voltage characteristics. The goals of this project are to find and to understand such new effects. Complementary theoretical methods appropriate for weak and strong coupling between the nanostructure and the leads will be used to achieve these goals.