[Fermions de Majorana libres avec des fils supraconducteurs et une impureté magnétique]
Through the two-channel Kondo model, I address a magnetic spin-1/2 impurity interacting with a bound state of spin origin at the edge in a Luther–Emery liquid showing a spin gap in the bulk. The system presents two zero-energy Majorana fermions of magnetic origin, one on the impurity site and one at the edge. I derive the wavefunction at the edge for the produced zero-energy Majorana fermion bound state within the same formalism as topological interfaces. I present alternative versions of the quantum field theory revealing the specific pairing of the Majorana fermions in the bulk. I address local physical responses. I develop the idea that this model can be realized with a magnetic impurity bridging the gap between two s-wave superconducting wires. I show the protection of the zero-energy Majorana fermions that will be referred to as free Majorana fermions.
À travers l’effet Kondo à deux canaux, j’adresse la physique d’une impureté magnétique interagissant avec un état de bords dans le liquide de Luther–Emery montrant un gap (hiatus) de spin dans le « bulk » du système. Le système présente deux fermions de Majorana à zéro énergie d’origine magnétique, l’un se formant sur le site de l’impureté et l’autre au bord. Je dérive la fonction d’onde pour le fermion de Majorana au bord dans un formalisme d’interface topologique. Je présente des formes variées et équivalentes de théorie quantique des champs révélant aussi le « couplage » des fermions de Majorana dans le cœur du système. Je discute des réponses physiques locales. Je développe ensuite l’idée que ce modèle peut être réalisé avec une impureté magnétique faisant le pont entre deux fils supraconducteurs de type s-wave. Je montre la protection des fermions de Majorana (à zéro énergie) qui sont introduits dans le titre comme fermions de Majorana libres.
Accepté le :
Publié le :
Mots-clés : Fermion de Majorana, fils quantiques, supraconducteurs, couplage magnétique
Karyn Le Hur 1
CC-BY 4.0
Karyn Le Hur. Free Majorana fermions with superconducting quantum wires and a magnetic impurity. Comptes Rendus. Physique, Volume 27 (2026), pp. 307-322. doi: 10.5802/crphys.284
@article{CRPHYS_2026__27_G1_307_0,
author = {Karyn Le Hur},
title = {Free {Majorana} fermions with superconducting quantum wires and a magnetic impurity},
journal = {Comptes Rendus. Physique},
pages = {307--322},
year = {2026},
publisher = {Acad\'emie des sciences, Paris},
volume = {27},
doi = {10.5802/crphys.284},
language = {en},
}
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