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Probing Majorana localization in minimal Kitaev chains through a quantum dot

Souto, Rubén Seoane LU orcid ; Tsintzis, Athanasios LU ; Leijnse, Martin LU and Danon, Jeroen (2023) In Physical Review Research 5(4).
Abstract

Artificial Kitaev chains, formed by quantum dots coupled via superconductors, have emerged as a promising platform for realizing Majorana bound states. Even a minimal Kitaev chain (a quantum dot-superconductor-quantum dot setup) can host Majorana states at discrete sweet spots. However, unambiguously identifying Majorana sweet spots in such a system is still challenging. In this work, we propose an additional dot coupled to one side of the chain as a tool to identify good sweet spots in minimal Kitaev chains. When the two Majorana states in the chain overlap, the extra dot couples to both and thus splits an even-odd ground-state degeneracy when its level is on resonance. In contrast, a ground-state degeneracy will persist for... (More)

Artificial Kitaev chains, formed by quantum dots coupled via superconductors, have emerged as a promising platform for realizing Majorana bound states. Even a minimal Kitaev chain (a quantum dot-superconductor-quantum dot setup) can host Majorana states at discrete sweet spots. However, unambiguously identifying Majorana sweet spots in such a system is still challenging. In this work, we propose an additional dot coupled to one side of the chain as a tool to identify good sweet spots in minimal Kitaev chains. When the two Majorana states in the chain overlap, the extra dot couples to both and thus splits an even-odd ground-state degeneracy when its level is on resonance. In contrast, a ground-state degeneracy will persist for well-separated Majorana states. This difference can be used to identify points in parameter space with spatially separated Majorana states, using tunneling spectroscopy measurements. We perform a systematic analysis of different relevant situations. We show that the additional dot can help distinguish between Majorana sweet spots and other trivial zero-energy crossings. We also characterize the different conductance patterns, which can serve as a guide for future experiments aiming to study Majorana states in minimal Kitaev chains.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review Research
volume
5
issue
4
article number
043182
publisher
American Physical Society
external identifiers
  • scopus:85179006863
ISSN
2643-1564
DOI
10.1103/PhysRevResearch.5.043182
language
English
LU publication?
yes
id
4b14a99b-470e-4225-a743-63b1d3cbc37b
date added to LUP
2024-01-09 11:09:29
date last changed
2024-01-09 11:09:29
@article{4b14a99b-470e-4225-a743-63b1d3cbc37b,
  abstract     = {{<p>Artificial Kitaev chains, formed by quantum dots coupled via superconductors, have emerged as a promising platform for realizing Majorana bound states. Even a minimal Kitaev chain (a quantum dot-superconductor-quantum dot setup) can host Majorana states at discrete sweet spots. However, unambiguously identifying Majorana sweet spots in such a system is still challenging. In this work, we propose an additional dot coupled to one side of the chain as a tool to identify good sweet spots in minimal Kitaev chains. When the two Majorana states in the chain overlap, the extra dot couples to both and thus splits an even-odd ground-state degeneracy when its level is on resonance. In contrast, a ground-state degeneracy will persist for well-separated Majorana states. This difference can be used to identify points in parameter space with spatially separated Majorana states, using tunneling spectroscopy measurements. We perform a systematic analysis of different relevant situations. We show that the additional dot can help distinguish between Majorana sweet spots and other trivial zero-energy crossings. We also characterize the different conductance patterns, which can serve as a guide for future experiments aiming to study Majorana states in minimal Kitaev chains.</p>}},
  author       = {{Souto, Rubén Seoane and Tsintzis, Athanasios and Leijnse, Martin and Danon, Jeroen}},
  issn         = {{2643-1564}},
  language     = {{eng}},
  number       = {{4}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review Research}},
  title        = {{Probing Majorana localization in minimal Kitaev chains through a quantum dot}},
  url          = {{http://dx.doi.org/10.1103/PhysRevResearch.5.043182}},
  doi          = {{10.1103/PhysRevResearch.5.043182}},
  volume       = {{5}},
  year         = {{2023}},
}