Observation of edge and bulk states in a three-site Kitaev chain

• 成果类型: Article
• 署名作者: ten Haaf, Sebastiaan L. D.; Zhang, Yining; Wang, Qingzhen; Bordin, Alberto; Liu, Chun-Xiao; Kulesh, Ivan; Sietses, Vincent P. M.; Prosko, Christian G.; Xiao, Di; Thomas, Candice; Manfra, Michael J.; Wimmer, Michael; Goswami, Srijit
• 署名单位: Delft University of Technology; Delft University of Technology; Purdue University System; Purdue University; Purdue University System; Purdue University; Purdue University in Indianapolis; Purdue University System; Purdue University
• 刊物名称: Nature
• ISSN/ISSBN: 0028-1688
• DOI: 10.1038/s41586-025-08892-5
• 发表日期: 2025-05-22
• 关键词: quantum; conductance

摘要

A chain of quantum dots (QDs) in semiconductor-superconductor hybrid systems can form an artificial Kitaev chain hosting Majorana bound states (MBSs)(1,2,3). These zero-energy states are expected to be localized on the edges of the chain(4), at the outermost QDs. The remaining QDs, comprising the bulk, are predicted to host an excitation gap that protects the MBSs at the edges from local on-site perturbations. Here we demonstrate this connection between the bulk and edges in a minimal system, by engineering a three-site Kitaev chain in a two-dimensional electron gas. Through direct tunnelling spectroscopy on each site, we show that the appearance of stable zero-bias conductance peaks at the outer QDs is correlated with the presence of an excitation gap in the middle QD. Furthermore, we show that this gap can be controlled by applying a superconducting phase difference between the two hybrid segments and that the MBSs are robust only when the excitation gap is present. We find a close agreement between experiments and the original Kitaev model, thus confirming key predictions for MBSs in a three-site chain.