Tunable Fano and Dicke effects in quantum transport of double quantum dots sandwiched between topological insulators

TL;DR

This paper investigates quantum transport in double quantum dots between topological insulator surfaces, revealing tunable Fano and Dicke effects, conductance scaling, and symmetry-dependent features influenced by spin-orbit coupling and external magnetic fields.

Contribution

It demonstrates how surface state mediated interactions induce tunable Fano and Dicke effects in quantum transport through double quantum dots with strong spin-orbit coupling.

Findings

Universal conductance scaling with Fermi energy

Tunable Fano and Dicke effects via inter-dot distance

Conductance pattern reveals system symmetry

Abstract

We study the quantum transport in double quantum dots (DQD) sandwiched between surfaces of topological insulator (TI) Bi$_{2}$Te$_{3}$, which possess strong spin-orbit coupling (SOC) and $^{d}$C$_{3v}$ double group symmetry. Different from the spin-conserved case with two-dimensional electron gas (2DEG) electrodes, the conductance displays a universal scaling relation for different Fermi energy associated with the topological nature/linear dispersion of topological surface states. The interplay between direct inter-dot tunneling and surface state mediated interaction leads to tunable Dicke and Fano effects with changing the inter-dot distance. We propose nano-rulers with different measurement range and resolution based on the Fano $q$-factor. Furthermore, when applying an in-plane Zeeman field, a crossover from a double-peak shape to a quad-peak shape in conductance curve appears. Moreover, the rotational symmetry of the system could also be revealed from the conductance pattern. Our findings contribute to a better understanding of the quantum transport in the presence of electrode's SOC topological states.