Majorana-Kondo interplay in T-shaped double quantum dots

Abstract

The transport behavior of a double quantum dot side-attached to a topological superconducting wire hosting Majorana zero-energy modes is studied theoretically in the strong correlation regime. It is shown that the Majorana zero energy mode can leak through the dot directly attached to topological superconductor to the side attached dot, giving rise to a subtle interplay between the two-stage Kondo screening and the half-fermionic nature of Majorana quasiparticles. In particular, the coupling to the topological wire is found to reduce the effective exchange interaction between the two quantum dots in the absence of normal leads. Interestingly, it also results in an enhancement of the second-stage Kondo temperature when the normal leads are attached. Moreover, it is shown that the second stage of the Kondo effect can become significantly modified in one of the spin channels due to the interference with the Majorana zero-energy mode, yielding the low-temperature conductance equal to G = G0/4, where G0 = 2e 2 /h, instead of G = 0 in the absence of the topological superconducting wire. Finally, in the case of a short wire, a finite overlap between the wave functions of the Majorana quasiparticles localized at the ends of the wire suppresses the quantum interference and a regular two-stage Kondo effect is restored.

Dual Majorana universality in thermally induced nonequilibrium

“…to use positive values of d to disentangle Majorana universality from Kondo universality in more general interacting setups [35,36]. As it is known [37], the Kondo universality may arise when d < 0.…”