马约拉纳费米子提供了诸如非阿贝尔统计和非局域鲁棒量子比特等迷人的可能性，探寻它成为了当前凝聚态物理学中最重要的课题之一。大部分研究精力都集中在利用扫描隧道谱学，寻找零能量下的马约拉纳束缚态，以探测量子化电导。另一方面，当在邻近诱导的超导性和铁磁性之间构建界面时，三维拓扑绝缘体的表面会出现手性马约拉纳边缘通道。近期，拓扑边缘态的微波谱学研究进展为通过局部光导率，观测这类马约拉纳边缘态的特征开辟了新的途径。
作为对未来实验的指导，该研究团队演示了局部光导率和态密度，如何根据超导性的对称性呈现出不同的定性特征，而这些特征可通过调节磁化强度和温度来调控。特别是，马约拉纳边缘态的存在，导致了一种特征性的非单调温度依赖性，这是通过调节磁化强度来实现的。
附：英文原文
Title: Optical conductivity of the Majorana mode at the s- and d-wave topological superconductor edge
Author: Kamra, Lina Johnsen, Lu, Bo, Linder, Jacob, Tanaka, Yukio, Nagaosa, Naoto
Issue&Volume: 2024-9-25
Abstract: The Majorana fermion offers fascinating possibilities such as non-Abelian statistics and nonlocal robust qubits, and hunting it is one of the most important topics in current condensed matter physics. Most of the efforts have been focused on the Majorana bound state at zero energy in terms of scanning tunneling spectroscopy searching for the quantized conductance. On the other hand, a chiral Majorana edge channel appears at the surface of a three-dimensional topological insulator when engineering an interface between proximity-induced superconductivity and ferromagnetism. Recent advances in microwave spectroscopy of topological edge states open a new avenue for observing signatures of such Majorana edge states through the local optical conductivity. As a guide to future experiments, we show how the local optical conductivity and density of states present distinct qualitative features depending on the symmetry of the superconductivity, that can be tuned via the magnetization and temperature. In particular, the presence of the Majorana edge state leads to a characteristic nonmonotonic temperature dependence achieved by tuning the magnetization.
DOI: 10.1073/pnas.2404009121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2404009121