Eur. Phys. J. B (2016) 89: 251
https://doi.org/10.1140/epjb/e2016-70477-7

Regular Article

Junction of three off-critical quantum Ising chains and two-channel Kondo effect in a superconductor

¹ Dipartimento di Fisica, Università della Calabria Arcavacata di Rende, 87036 Cosenza, Italy
² I.N.F.N., Gruppo collegato di Cosenza, Arcavacata di Rende, 87036 Cosenza, Italy
³ Dipartimento di Fisica, Università di Napoli “Federico II” and CNR-SPIN, Monte S. Angelo-Via Cintia, 80126 Napoli, Italy

^a e-mail: domenico.giuliano@fis.unical.it

Received: 11 August 2016
Received in final form: 26 September 2016
Published online: 21 November 2016

Abstract

We show that a junction of three off-critical quantum Ising chains can be regarded as a quantum spin chain realization of the two-channel spin-1/2 overscreened Kondo effect with two superconducting leads. We prove that, as long as the Kondo temperature is larger than the superconducting gap, the equivalent Kondo model flows towards the two channel Kondo fixed point. We argue that our system provides the first controlled realization of two channel Kondo effect with superconducting leads. Besides its theoretical interest, this result is of importance for potential applications to a number of contexts, including the analysis of the quantum entanglement properties of a Kondo system.