Effects of anisotropy and Coulomb interactions on quantum transport in a quadruple quantum-dot structure

Abstract

We present analytical and numerical investigation of spectral and transport properties of a quadruple quantum-dot (QQD) structure which is one of the popular low-dimensional systems in the context of fundamental quantum physics study, future electronic applications and quantum calculations. The density of states, occupation numbers and conductance of the structure were analyzed using the nonequilibrium Green's functions in the tight binding approach and the equation-of-motion method. In particular the anisotropy of hopping integrals and on-site electron energies as well as the effects of the finite intraand interdot Coulomb interactions were investigated. It was found out that the anisotropy of the kinetic processes in the system leads to the Fano-Feshbach asymmetrical peak. We demonstrated that the conductance of QQD device has a wide insulating band with steep edges separating triple-peak structures if the intradot Coulomb interactions are taken into account. The interdot Coulomb correlations between the central QDs result in the broadening of this band and the occurrence of an additional band with low conductance due to the Fano antiresonances. It was shown that in this case the conductance of the anisotropic QQD device can be dramatically changed by tuning the anisotropy of on-site electron energies.

Capillary-driven elastic attraction between quantum dots

“…QDs are now commonly manufactured by different techniques, from colloidal synthesis, lithography, 3D printing to epitaxy, and are used for many different purposes in fundamental systems, such as in quantum photonics, lasing or excitonic systems [5][6][7][8][9][10][11][12][13][14][15][16] , and in commercial devices such as screen displays or memories [17][18][19][20][21][22] . Recently with the renewed interest in quantum dots based quantum information [23][24][25] it has become highly challenging to self-organize limited assemblies of laterally close packed quantum dots [26][27][28][29][30][31][32] . The technique best suited for device integration is epitaxy where quantum dots growth is driven by the elastic relaxation of the misfit strain.…”

Influence of Coulomb Correlations on Nonequilibrium Quantum Transport in a Quadruple Quantum-Dot Structure

“…Simultaneously, the Fano antiresonances in the conductance emerging due to the Coulomb interaction between the central dots [25,26] are modified if eV = 0. Both insulating bands obtained in the linear response regime persist at eV = 0.5.…”

“…In particular, the induction of asymmetric Fano peaks at V = 0 is attributed to the appearance of corresponding maxima in the dependence T DOS (ω) [25,26]. In turn, the BICs do not manifest themselves in the QQD transport characteristics.…”

“…Next, to derive the closed systems of equations we use the decoupling procedure for the nonmagnetic case developed in the refs. [24][25][26]. Such an approximation is valid at temperatures higher than the Kondo temperature [27].…”

Probing and driving of spin and charge states in double quantum dot under the quench

“…The possibility of QDs integration in a small size quantum circuits deals with careful analysis of relaxation processes and non-stationary effects influence on the electron transport through the dots system 22–31 . Moreover, electronic transport in such systems is strongly influenced by the inter-particle interaction (Coulomb correlations, electron-phonon interaction, the ratio between the QDs coupling and interaction with the reservoir) 32–35 . Electron transport peculiarities through nanoscale systems also depend on the system symmetry properties, geometry of the experimental setup and the way of switching to reservoir 36,37 .…”