Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA.
Rep Prog Phys. 2012 Jul;75(7):076501. doi: 10.1088/0034-4885/75/7/076501. Epub 2012 Jun 28.
The 1937 theoretical discovery of Majorana fermions-whose defining property is that they are their own anti-particles-has since impacted diverse problems ranging from neutrino physics and dark matter searches to the fractional quantum Hall effect and superconductivity. Despite this long history the unambiguous observation of Majorana fermions nevertheless remains an outstanding goal. This review paper highlights recent advances in the condensed matter search for Majorana that have led many in the field to believe that this quest may soon bear fruit. We begin by introducing in some detail exotic 'topological' one- and two-dimensional superconductors that support Majorana fermions at their boundaries and at vortices. We then turn to one of the key insights that arose during the past few years; namely, that it is possible to 'engineer' such exotic superconductors in the laboratory by forming appropriate heterostructures with ordinary s-wave superconductors. Numerous proposals of this type are discussed, based on diverse materials such as topological insulators, conventional semiconductors, ferromagnetic metals and many others. The all-important question of how one experimentally detects Majorana fermions in these setups is then addressed. We focus on three classes of measurements that provide smoking-gun Majorana signatures: tunneling, Josephson effects and interferometry. Finally, we discuss the most remarkable properties of condensed matter Majorana fermions-the non-Abelian exchange statistics that they generate and their associated potential for quantum computation.
1937 年，马约拉纳费米子的理论发现——其定义特征是它们自身的反粒子——自此影响了从中微子物理和暗物质搜索到分数量子霍尔效应和超导性等各种问题。尽管有着悠久的历史，但马约拉纳费米子的明确观测仍然是一个未竟的目标。本文综述了凝聚态物质中寻找马约拉纳费米子的最新进展，这些进展使得该领域的许多人相信，这一探索可能很快就会有成果。我们首先详细介绍了支持边界和涡旋处存在马约拉纳费米子的奇异“拓扑”一维和二维超导体。然后，我们转向过去几年出现的一个关键见解，即通过与普通 s 波超导体形成适当的异质结构，可以在实验室中“设计”这种奇异超导体。基于拓扑绝缘体、常规半导体、铁磁金属等多种材料，讨论了许多这类的提案。然后，我们讨论了如何在这些设置中通过实验检测马约拉纳费米子的至关重要的问题。我们重点介绍了提供确凿马约拉纳特征的三类测量：隧道效应、约瑟夫森效应和干涉测量。最后，我们讨论了凝聚态物质马约拉纳费米子最显著的性质——它们产生的非阿贝尔交换统计及其在量子计算中的潜在应用。
