Multichannel topological Kondo models and their low-temperature conductances, by Guangjie Li, Elio J. König, Jukka I. Väyrynen

SciPost Physics Home Authoring Refereeing Submit a manuscript About Multichannel topological Kondo models and their low-temperature conductances Guangjie Li, Elio J. König, Jukka I. Väyrynen SciPost Phys. 20, 032 (2026) · published 5 February 2026 doi: 10.21468/SciPostPhys.20.2.032 pdf BiBTeX RIS Submissions/Reports Abstract In the multichannel Kondo effect, overscreening of a magnetic impurity by conduction electrons leads to a frustrated exotic ground state. It has been proposed that multichannel topological Kondo (MCTK) model involving topological Cooper pair boxes with $M$ Majorana modes [SO($M$) "spin"] and $N$ spinless electron channels exhibits an exotic intermediate coupling fixed point. This intermediate fixed point has been analyzed through large-$N$ perturbative calculations, which gives a zero-temperature conductance decaying as $1/N^2$ in the large-$N$ limit. However, the conductance at this intermediate fixed point has not been calculated for generic $N$. Using representation theory, we verify the existence of this intermediate-coupling fixed point and find the strong-coupling effective Hamiltonian for the case $M=4$. Using conformal field theory techniques for SO($M$), we generalize the notion of overscreening and conclude that the MCTK model is an overscreened Kondo model. We find the fixed-point finite-size energy spectrum and the leading irrelevant operator (LIO). We express the fixed-point conductance in terms of the modular S-matrix of SO($M$) for general $N$, confirming the previous large-$N$ result. We describe the finite-temperature corrections to the conductance by the LIO and find that they are qualitatively different for the cases $N=1$ and $N≥2$ due to the different fusion outcomes with the current operator. We also compare the multichannel topological Kondo model to the topological symplectic Kondo model. × TY - JOURPB - SciPost FoundationDO - 10.21468/SciPostPhys.20.2.032TI - Multichannel topological Kondo models and their low-temperature conductancesPY - 2026/02/05UR - https://scipost.org/SciPostPhys.20.2.032JF - SciPost PhysicsJA - SciPost Phys.VL - 20IS - 2SP - 032A1 - Li, GuangjieAU - König, Elio J.AU - Väyrynen, Jukka I.AB - In the multichannel Kondo effect, overscreening of a magnetic impurity by conduction electrons leads to a frustrated exotic ground state. It has been proposed that multichannel topological Kondo (MCTK) model involving topological Cooper pair boxes with $M$ Majorana modes [SO($M$) "spin"] and $N$ spinless electron channels exhibits an exotic intermediate coupling fixed point. This intermediate fixed point has been analyzed through large-$N$ perturbative calculations, which gives a zero-temperature conductance decaying as $1/N^2$ in the large-$N$ limit. However, the conductance at this intermediate fixed point has not been calculated for generic $N$. Using representation theory, we verify the existence of this intermediate-coupling fixed point and find the strong-coupling effective Hamiltonian for the case $M=4$. Using conformal field theory techniques for SO($M$), we generalize the notion of overscreening and conclude that the MCTK model is an overscreened Kondo model. We find the fixed-point finite-size energy spectrum and the leading irrelevant operator (LIO). We express the fixed-point conductance in terms of the modular S-matrix of SO($M$) for general $N$, confirming the previous large-$N$ result. We describe the finite-temperature corrections to the conductance by the LIO and find that they are qualitatively different for the cases $N=1$ and $N≥2$ due to the different fusion outcomes with the current operator. We also compare the multichannel topological Kondo model to the topological symplectic Kondo model.ER - × @Article{10.21468/SciPostPhys.20.2.032, title={{Multichannel topological Kondo models and their low-temperature conductances}}, author={Guangjie Li and Elio J. König and Jukka I. Väyrynen}, journal={SciPost Phys.}, volume={20}, pages={032}, year={2026}, publisher={SciPost}, doi={10.21468/SciPostPhys.20.2.032}, url={https://scipost.org/10.21468/SciPostPhys.20.2.032},} Ontology / Topics See full Ontology or Topics database. Conductance Conformal field theory (CFT) Kondo model Non-abelian symmetries Quantum impurity problems Authors / Affiliations: mappings to Contributors and Organizations See all Organizations. 1 2 Guangjie Li, 3 4 Elio J. König, 1 Jukka I. Väyrynen 1 Purdue University 2 University of Utah [UU] 3 University of Wisconsin–Madison [UW] 4 Max-Planck-Institut für Festkörperforschung / Max Planck Institute for Solid State Research Funders for the research work leading to this publication National Science Foundation [NSF] United States Department of Energy [DOE] University of Wisconsin-Madison