Transport features of a topological superconducting nanowire with a quantum dot: Conductance and noise

Leonel Gruñeiro, Miguel Alvarado, Alfredo Levy Yeyati, and Liliana Arrachea
Phys. Rev. B 108, 045418 – Published 24 July 2023

Abstract

We study two-terminal configurations in junctions between a topological superconducting wire with spin-orbit coupling and magnetic field, and an ordinary conductor with an embedded quantum dot. One of the signatures of the Majorana zero modes in the topological phase is a quantization of the zero-bias conductance at G(V=0)=2e2/h. However, the finite size of the wires and the presence of the quantum dot in the junction generate more complicated features, which lead to deviations from this simple picture. Here, we analyze the behavior of the conductance at zero and finite bias G(V) as a function of a gate voltage applied at the quantum dot in the case of a finite-length wire. We analyze the effect of the angle between the magnetic field and the orientation associated to the spin-orbit coupling. We provide a detailed description of the spectral features of the quantum wire weakly and also strongly coupled to the quantum dot and describe the conditions to have zero-energy states in these two regimes for both the topological and nontopological phases. We also analyze the concomitant behavior of the noise. We identify qualitative features that are useful to distinguish between the topological and nontopological phases. We show that in a strongly coupled quantum dot the simultaneous hybridization with the topological modes and the supragap states of the wire mask the signatures of the Majorana bound states in both the conductance and the Fano factor.

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  • Received 8 May 2023
  • Revised 13 July 2023
  • Accepted 14 July 2023

DOI:https://doi.org/10.1103/PhysRevB.108.045418

©2023 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Leonel Gruñeiro1,*, Miguel Alvarado2,*, Alfredo Levy Yeyati2, and Liliana Arrachea1

  • 1Escuela de Ciencia y Tecnología and ICIFI, Universidad Nacional de San Martín-UNSAM, Av 25 de Mayo y Francia, 1650 Buenos Aires, Argentina
  • 2Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC) and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid, Spain

  • *These authors contributed equally to this work.

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Issue

Vol. 108, Iss. 4 — 15 July 2023

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