Electronic Structure of Quantum Dot: Tight-Binding Approach.

Semiconductor quantum dots are of particular interest, both for fundamental research and possible applications. Quantum dots are considered to be artificial atoms for which shape and properties can be manipulated. Due to the lattice mismatch between quantum dot and surrounding material, it is essential to investigate the influence of the strain distribution: here we use the Valence Force Field method. The strain-induced confinement potentials of the Quantum dot was investigated in terms of the eight-band strain-dependent k.p approach. In order to study the electronic properties of Group IV and III-V quantum dots, the sp3s* empirical tight-binding method has been used. We implement this method to investigate the electronic structure and application of quantum dot in the view of Quantum Computing. We have shown, for example, that the leakage of quantum information in a double-dot electric field driven qubit gate is strongly influenced by the geometry of double quantum dot and the amplitude of the electric pulse

Strain-Induced Band Profile of Stacked InAs/GaAs Quantum Dots

The strain distribution and band profile in triply stacked InAs/GaAs quantum dots with dot spacing of 0.0 - 6.0 nm was calculated. The continuum elasticity theory for strain distribution and 8-band k.p theory for band structure was used. The use of the k.p method to calculate band structure with and without including the effects of strain is reported. The calculated results show the importance of strain effect on the confinement potential of the band structure for triply stacked InAs/GaAs quantum dots. doi:10.14456/WJST.2014.1

Electronic Structure of Quantum Dot: Tight-Binding Approach.

Semiconductor quantum dots are of particular interest, both for fundamental research and possible applications. Quantum dots are considered to be artificial atoms for which shape and properties can be manipulated. Due to the lattice mismatch between quantum dot and surrounding material, it is essential to investigate the influence of the strain distribution: here we use the Valence Force Field method. The strain-induced confinement potentials of the Quantum dot was investigated in terms of the eight-band strain-dependent k.p approach. In order to study the electronic properties of Group IV and III-V quantum dots, the sp3s* empirical tight-binding method has been used. We implement this method to investigate the electronic structure and application of quantum dot in the view of Quantum Computing. We have shown, for example, that the leakage of quantum information in a double-dot electric field driven qubit gate is strongly influenced by the geometry of double quantum dot and the amplitude of the electric pulse

Atomistic Tight-Binding Theory of Electron-Hole Exchange Interaction in Morphological Evolution of CdSe/ZnS Core/Shell Nanodisk to CdSe/ZnS Core/Shell Nanorod

Based on the atomistic tight-binding theory (TB) and a configuration interaction (CI) description, the electron-hole exchange interaction in the morphological transformation of CdSe/ZnS core/shell nanodisk to CdSe/ZnS core/shell nanorod is described with the aim of understanding the impact of the structural shapes on the change of the electron-hole exchange interaction. Normally, the ground hole states confined in typical CdSe/ZnS core/shell nanocrystals are of heavy hole-like character. However, the atomistic tight-binding theory shows that a transition of the ground hole states from heavy hole-like to light hole-like contribution with the increasing aspect ratios of the CdSe/ZnS core/shell nanostructures is recognized. According to the change in the ground-state hole characters, the electron-hole exchange interaction is also significantly altered. To do so, optical band gaps, ground-state electron character, ground-state hole character, oscillation strengths, ground-state coulomb energies, ground-state exchange energies, and dark-bright (DB) excitonic splitting (stoke shift) are numerically demonstrated. These atomistic computations obviously show the sensitivity with the aspect ratios. Finally, the alteration in the hole character has a prominent effect on dark-bright (DB) excitonic splitting

Dynamical Behavior of Two Interacting Double Quantum Dots in 2D Materials for Feasibility of Controlled-NOT Operation

Two interacting double quantum dots (DQDs) can be suitable candidates for operation in the applications of quantum information processing and computation. In this work, DQDs are modeled by the heterostructure of two-dimensional (2D) MoS2 having 1T-phase embedded in 2H-phase with the aim to investigate the feasibility of controlled-NOT (CNOT) gate operation with the Coulomb interaction. The Hamiltonian of the system is constructed by two models, namely the 2D electronic potential model and the 4×4 matrix model whose matrix elements are computed from the approximated two-level systems interaction. The dynamics of states are carried out by the Crank–Nicolson method in the potential model and by the fourth order Runge–Kutta method in the matrix model. Model parameters are analyzed to optimize the CNOT operation feasibility and fidelity, and investigate the behaviors of DQDs in different regimes. Results from both models are in excellent agreement, indicating that the constructed matrix model can be used to simulate dynamical behaviors of two interacting DQDs with lower computational resources. For CNOT operation, the two DQD systems with the Coulomb interaction are feasible, though optimization of engineering parameters is needed to achieve optimal fidelity