Subtle leakage of a Majorana mode into a quantum dot

By E. Vernek, P. Penteado, A. Seridonio, J. C. Egues. 2013

134 citations recorded by the source corpus.

We investigate quantum transport through a quantum dot connected to source and drain leads and side coupled to a topological superconducting nanowire (Kitaev chain) sustaining Majorana end modes. Using a recursive Green’s-function approach, we determine the local density of states of the system and find that the end Majorana mode of the wire leaks into the dot, thus, emerging as a unique dot level pinned to the Fermi energy eF of the leads. Surprisingly, this resonance pinning, resembling, in this sense, a “Kondo resonance,” occurs even when the gate-controlled dot level edot(Vg) is far above or far below eF . The calculated conductance G of the dot exhibits an unambiguous signature for the Majorana end mode of the wire: In essence, an off-resonance dot [edot(Vg) � eF ], which should have G = 0, shows, instead, a conductance e 2 /2h over a wide range of Vg due to this pinned dot mode. Interestingly, this pinning effect only occurs when the dot level is coupled to a Majorana mode; ordinary fermionic modes (e.g., disorder) in the wire simply split and broaden (if a continuum) the dot level. We discuss experimental scenarios to probe Majorana modes in wires via these leaked/pinned dot modes.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/9229e06d6946495a09f82c2c279fd5829143a686