Kondo physics from quasiparticle poisoning in Majorana devices

Article

关键词: SEMICONDUCTOR-SUPERCONDUCTOR NANOWIRES;    FERMIONS;    STATES;   

DOI  :  10.1103/PhysRevB.93.104524

来源: SCIE

【 摘 要 】

We present a theoretical analysis of quasiparticle poisoning in Coulomb-blockaded Majorana fermion systems tunnel-coupled to normal-conducting leads. Taking into account finite-energy quasiparticles, we derive the effective low-energy theory and present a renormalization group analysis. We find qualitatively new effects when a quasiparticle state with very low energy is localized near a tunnel contact. For M = 2 attached leads, such dangerous quasiparticle poisoning processes cause a spin S = 1/2 single-channel Kondo effect, which can be detected through a characteristic zero-bias anomaly conductance peak in all Coulomb blockade valleys. For more than two attached leads, the topological Kondo effect of the unpoisoned system becomes unstable. A strong-coupling bosonization analysis indicates that at low energy the poisoned lead is effectively decoupled and hence, forM > 3, the topological Kondo fixed point re-emerges, though now it involves only M - 1 leads. As a consequence, for M = 3, the low-energy fixed point becomes trivial corresponding to decoupled leads.

【 授权许可】

Free