Kondo-based Qubits for Topological Quantum Computation

TL;DR

This paper explores the use of residual parafermions from the overscreened Kondo effect as a platform for topological quantum computation, highlighting their stability under certain superconducting conditions.

Contribution

It introduces a superconducting charge Kondo setup that stabilizes residual parafermions, proposing a new approach for isolating and detecting Majorana fermions.

Findings

Residual entropy of multichannel Kondo impurities persists in superconductors.

Non-trivial fixed point is stable with inter-channel pairing but unstable with intra-channel pairing.

Proposes a superconducting charge Kondo device for Majorana fermion detection.

Abstract

We propose to use residual parafermions of the overscreened Kondo effect for topological quantum computation. A superconducting proximity gap of $\Delta<T_K$ can be utilized to isolate the parafermion from the continuum of excitations and stabilize the non-trivial fixed point. We use weak-coupling renormalization group, dynamical large-N technique and bosonization to show that the residual entropy of multichannel Kondo impurities survives in a superconductor. We find that while (in agreement with recent numerical studies) the non-trivial fixed point is unstable against intra-channel pairing, it is robust in presence of a finite inter-channel pairing. Based on this observation, we suggest a superconducting charge Kondo setup for isolating and detecting the Majorana fermion in the two-channel Kondo system.