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

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 2 channel Kondo fixed point. We argue that our system provides the first controlled realization of 2 channel Kondo effect with superconducting leads. This, besides its the theoretical interest, is of importance for potential applications to a number of context, including the analysis of the quantum entanglement properties of a Kondo system.