Majorana quasiparticles in atomic spin chains on superconductors

TL;DR

This paper reviews recent progress in creating and detecting Majorana quasiparticles in atomic spin chains on superconductors, emphasizing their potential for topological quantum computing and the importance of atomic-scale control.

Contribution

It highlights the significance of atom-by-atom fabrication of spin chains on superconductors for studying Majorana states and discusses recent experimental advances in this area.

Findings

Atomic spin chains enable detailed study of Majorana states.

Disorder-free chains improve the clarity of Majorana detection.

Topological sub-gap Shiba bands observed in atomic chains.

Abstract

For the past decade, Majorana quasiparticles have become one of the hot topics in condensed matter research. Besides the fundamental interest in the realization of particles being their own antiparticles, going back to basic concepts of elementary particle physics, Majorana quasiparticles in condensed matter systems offer exciting potential applications in topological quantum computation due to their non-Abelian quantum exchange statistics. Motivated by theoretical predictions about possible realizations of Majorana quasiparticles as zero-energy modes at boundaries of topological superconductors, experimental efforts have focussed in particular on quasi-one-dimensional semiconductor-superconductor and magnet-superconductor hybrid systems. However, an unambiguous proof of the existence of Majorana quasiparticles is still challenging and requires considerable improvements in materials science, atomic-scale characterization and control of interface quality, as well as complementary approaches of detecting various facets of Majorana quasiparticles. Bottom-up atom-by-atom fabrication of disorder-free atomic spin chains on atomically clean superconducting substrates has recently allowed deep insight into the emergence of topological sub-gap Shiba bands and associated Majorana states from the level of individual atoms up to extended chains, thereby offering the possibility for critical tests of Majorana physics in disorder-free model-type 1D hybrid systems.