Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Majorana sweet spots in three-site Kitaev chains

Dourado, Rodrigo A. ; Leijnse, Martin LU and Souto, Rubén Seoane LU orcid (2025) In Physical Review B 111(23).
Abstract

Minimal Kitaev chains, composed of two quantum dots connected via a superconductor, have emerged as an attractive platform to realize Majorana bound states (MBSs). These excitations exist when the ground state is degenerate. The additional requirement of isolating the MBS wave functions further restricts the parameter space to discrete sweet spots. While scaling up to Kitaev chains with more than two sites has the potential to improve the stability of the MBSs, longer chains offer more features to optimize, including the MBS localization length and the excitation gap. In this work, we theoretically investigate three-site Kitaev chains and show that there are three different types of sweet spots, obtained by maximizing distinct MBS... (More)

Minimal Kitaev chains, composed of two quantum dots connected via a superconductor, have emerged as an attractive platform to realize Majorana bound states (MBSs). These excitations exist when the ground state is degenerate. The additional requirement of isolating the MBS wave functions further restricts the parameter space to discrete sweet spots. While scaling up to Kitaev chains with more than two sites has the potential to improve the stability of the MBSs, longer chains offer more features to optimize, including the MBS localization length and the excitation gap. In this work, we theoretically investigate three-site Kitaev chains and show that there are three different types of sweet spots, obtained by maximizing distinct MBS properties: genuine three-site sweet spots with well-localized MBSs at the ends, effective two-site sweet spots, where the middle site acts as a barrier, and sweet spots with delocalized MBSs that overlap in the middle of the chain. These three cases feature different degrees of robustness against perturbations, with the genuine three-site being the most stable. We analyze the energy spectrum, transport, and microwave absorption associated with these three cases, showing how to distinguish them.

(Less)
Please use this url to cite or link to this publication:
author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review B
volume
111
issue
23
article number
235409
publisher
American Physical Society
external identifiers
  • scopus:105007288481
ISSN
2469-9950
DOI
10.1103/PhysRevB.111.235409
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025 American Physical Society.
id
6945180d-7afe-4787-8398-832c7539bd22
date added to LUP
2026-01-12 09:05:01
date last changed
2026-01-12 15:29:15
@article{6945180d-7afe-4787-8398-832c7539bd22,
  abstract     = {{<p>Minimal Kitaev chains, composed of two quantum dots connected via a superconductor, have emerged as an attractive platform to realize Majorana bound states (MBSs). These excitations exist when the ground state is degenerate. The additional requirement of isolating the MBS wave functions further restricts the parameter space to discrete sweet spots. While scaling up to Kitaev chains with more than two sites has the potential to improve the stability of the MBSs, longer chains offer more features to optimize, including the MBS localization length and the excitation gap. In this work, we theoretically investigate three-site Kitaev chains and show that there are three different types of sweet spots, obtained by maximizing distinct MBS properties: genuine three-site sweet spots with well-localized MBSs at the ends, effective two-site sweet spots, where the middle site acts as a barrier, and sweet spots with delocalized MBSs that overlap in the middle of the chain. These three cases feature different degrees of robustness against perturbations, with the genuine three-site being the most stable. We analyze the energy spectrum, transport, and microwave absorption associated with these three cases, showing how to distinguish them.</p>}},
  author       = {{Dourado, Rodrigo A. and Leijnse, Martin and Souto, Rubén Seoane}},
  issn         = {{2469-9950}},
  language     = {{eng}},
  month        = {{06}},
  number       = {{23}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review B}},
  title        = {{Majorana sweet spots in three-site Kitaev chains}},
  url          = {{http://dx.doi.org/10.1103/PhysRevB.111.235409}},
  doi          = {{10.1103/PhysRevB.111.235409}},
  volume       = {{111}},
  year         = {{2025}},
}