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Poor Man’s Majorana Tetron

Nitsch, Maximilian LU orcid ; Maffi, Lorenzo ; Baran, Virgil V. ; Seoane Souto, Rubén LU orcid ; Paaske, Jens ; Leijnse, Martin LU and Burrello, Michele (2025) In PRX Quantum 6(3).
Abstract
The Majorana tetron is a prototypical topological qubit stemming from the ground-state degeneracy of a superconducting island hosting four Majorana modes. This degeneracy manifests as an effective nonlocal spin degree of freedom, the most paradigmatic signature of which is the topological Kondo effect. Degeneracies of states with different fermionic parities also characterize minimal Kitaev chains, which have lately emerged as a platform to realize and study unprotected versions of Majorana modes, dubbed poor man’s Majorana modes. Here, we introduce the “poor man’s Majorana tetron,” comprising four quantum dots coupled via a floating superconducting island. Its charging energy yields nontrivial correlations among the dots, although, unlike... (More)
The Majorana tetron is a prototypical topological qubit stemming from the ground-state degeneracy of a superconducting island hosting four Majorana modes. This degeneracy manifests as an effective nonlocal spin degree of freedom, the most paradigmatic signature of which is the topological Kondo effect. Degeneracies of states with different fermionic parities also characterize minimal Kitaev chains, which have lately emerged as a platform to realize and study unprotected versions of Majorana modes, dubbed poor man’s Majorana modes. Here, we introduce the “poor man’s Majorana tetron,” comprising four quantum dots coupled via a floating superconducting island. Its charging energy yields nontrivial correlations among the dots, although, unlike a standard tetron, it is not directly determined by the fermionic parity of the Majorana modes. The poor man’s tetron displays parameter regions with a twofold-degenerate ground state with odd fermionic parity, which gives rise to an effective Anderson impurity model when coupled to external leads. We show that this system can approach a regime featuring the topological Kondo effect under a suitable tuning of experimental parameters. Therefore, the poor man’s tetron is a promising device to observe the nonlocality of Majorana modes and their related fractional conductance. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
PRX Quantum
volume
6
issue
3
article number
030365
publisher
American Physical Society
ISSN
2691-3399
DOI
10.1103/r75t-jv32
language
English
LU publication?
yes
id
47a7c0a5-88a1-42d3-983b-3e49753ccf8d
date added to LUP
2025-11-06 11:12:37
date last changed
2025-11-10 13:47:44
@article{47a7c0a5-88a1-42d3-983b-3e49753ccf8d,
  abstract     = {{The Majorana tetron is a prototypical topological qubit stemming from the ground-state degeneracy of a superconducting island hosting four Majorana modes. This degeneracy manifests as an effective nonlocal spin degree of freedom, the most paradigmatic signature of which is the topological Kondo effect. Degeneracies of states with different fermionic parities also characterize minimal Kitaev chains, which have lately emerged as a platform to realize and study unprotected versions of Majorana modes, dubbed poor man’s Majorana modes. Here, we introduce the “poor man’s Majorana tetron,” comprising four quantum dots coupled via a floating superconducting island. Its charging energy yields nontrivial correlations among the dots, although, unlike a standard tetron, it is not directly determined by the fermionic parity of the Majorana modes. The poor man’s tetron displays parameter regions with a twofold-degenerate ground state with odd fermionic parity, which gives rise to an effective Anderson impurity model when coupled to external leads. We show that this system can approach a regime featuring the topological Kondo effect under a suitable tuning of experimental parameters. Therefore, the poor man’s tetron is a promising device to observe the nonlocality of Majorana modes and their related fractional conductance.}},
  author       = {{Nitsch, Maximilian and Maffi, Lorenzo and Baran, Virgil V. and Seoane Souto, Rubén and Paaske, Jens and Leijnse, Martin and Burrello, Michele}},
  issn         = {{2691-3399}},
  language     = {{eng}},
  month        = {{09}},
  number       = {{3}},
  publisher    = {{American Physical Society}},
  series       = {{PRX Quantum}},
  title        = {{Poor Man’s Majorana Tetron}},
  url          = {{http://dx.doi.org/10.1103/r75t-jv32}},
  doi          = {{10.1103/r75t-jv32}},
  volume       = {{6}},
  year         = {{2025}},
}