M.L. Ladrón de Guevara

TRANSPORT THROUGH A QUANTUM WIRE WITH A SIDE QUANTUM-DOT ARRAY

A noninteracting quantum-dot array side coupled to a quantum wire is studied. Transport through the quantum wire is investigated by using a noninteracting Anderson tunneling Hamiltonian. The conductance at zero temperature develops an oscillating band with resonances and antiresonances due to constructive and destructive interference in the ballistic channel, respectively. Moreover, we have found an odd-even parity in the system, whose conductance vanishes for an odd number of quantum dots while it becomes 2e(2)/h for an even number. We established an explicit relation between this odd-even parity and the positions of the resonances and antiresonances of the conductivity with the spectrum of the isolated quantum-dot array.

Electronic transport through a parallel-coupled triple quantum dot molecule : Fano resonances and bound states in the continuum

In this paper we study electronic transport through a triple quantum dot molecule attached in parallel to leads in presence of a magnetic flux. We have obtained analytical expressions of the linear conductance and density of states for the molecule in equilibrium at zero temperature. As a consequence of quantum interference, the conductance exhibits one Breit-Wigner and two Fano resonances, which positions and widths are controlled by the magnetic field. Every two flux quanta, there is an inversion of roles of the bonding and antibonding states. For particular values of the magnetic flux and dot-lead couplings, one or even both Fano resonances collapse and bound states in the continuum (BICs) are formed. We examine the line broadenings of the molecular states as a function of the Aharonov-Bohm phase around the condition for the formation of BICs, finding resonances which keep extremely narrow against variations of the magnetic field. Moreover, we analyze a molecule of

Controlling Fano and Dicke effects via a magnetic flux in a two-site Anderson model

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Conductance and persistent current of a quantum ring coupled to a quantum wire under external fields

quantum dots in the absence of magnetic field, showing that certain symmetries lead to a determinate quantity of simultaneous BICs.

Electronic transport through two double quantum dot molecules embedded in an Aharonov-Bohm ring

The electronic transport through a parallel double quantum-dot molecule attached asymmetrically to leads is studied under a magnetic field. We model the system by means of a non interacting two-impurity Anderson Hamiltonian. We find that the conductance shows Fano and Dicke effects that can be controlled by the magnetic flux.

Complex behavior of the conductance of quantum wires with a long quantum-dot array

The electronic transport of a noninteracting quantum ring side coupled to a quantum wire is studied via a single-band tunneling tight-binding Hamiltonian. We found that the system develops an oscillating band with antiresonances and resonances arising from the hybridization of the quasibound levels of the ring and the coupling to the quantum wire. The positions of the antiresonances correspond exactly to the electronic spectrum of the isolated ring. Moreover, for a uniform quantum ring the conductance and the persistent current density were found to exhibit a particular odd-even parity related with the ring order. The effects of an in-plane electric field were also studied. This field shifts the electronic spectrum and damps the amplitude of the persistent current density. These features may be used to control externally the energy spectra and the amplitude of the persistent current.

Ghost Fano resonance in a double quantum dot molecule attached to leads

We study transport through two quantum dot molecules embedded in an Aharonov-Bohm interferometer. We obtain analytically the conductance in equilibrium at zero temperature. As a result of quantum interference, this system exhibits up to two bound states in the continuum simultaneously, and remarkably maximum conductance occurs even when the molecules have both extremely weak interdot couplings.

Electronic transmission through a quantum wire by side-attached nanowires

We consider electron transport through a quantum wire with an attached quantum-dot array, when the number of dots is large. To this end, we use a noninteracting Anderson Hamiltonian. The conductance at zero temperature shows a complex behavior as a function of the Fermi energy. In particular, two well-defined energy regions are observed. Far from the site-energy of the quantum dots, the conductance depends smoothly on the Fermi energy. On the contrary, at the center of the band the conductance develops an oscillating pattern with resonances and antiresonances due to constructive and destructive interference in the ballistic channel, respectively. We discuss analytically in detail the physical origin of this complex behavior.