scholarly journals Orbital magnetization of single and double quantum dots in a tight-binding model

2003 ◽  
Vol 67 (3) ◽  
Author(s):  
A. Aldea ◽  
V. Moldoveanu ◽  
M. Niţă ◽  
A. Manolescu ◽  
V. Gudmundsson ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Tight Binding ◽  
Double Quantum ◽  
Tight Binding Model ◽  
Binding Model ◽  
Double Quantum Dots ◽  
Orbital Magnetization

scholarly journals Calculations on Electronic States in QDs with Saturated Shapes

2003 ◽  
Vol 02 (01n02) ◽  
pp. 37-48 ◽  
Author(s):  
Wei Cheng ◽  
Shang-Fen Ren
Keyword(s):  
Quantum Dots ◽  
Group Theory ◽  
Size Range ◽  
Tight Binding ◽  
Electronic States ◽  
Spherical Shape ◽  
Irreducible Representations ◽  
Tight Binding Model ◽  
Binding Model ◽  
Ge Quantum Dots

Electronic States of Si and Ge QDs of 5 to 3127 atoms with saturated shapes in a size range of 0.57 to 4.92 nm for Si and 0.60 to 5.13 nm for Ge are calculated by using an empirical tight-binding model combined with the irreducible representations of the group theory. The results are compared with those of Si and Ge quantum dots with spherical shape. The effects of the shapes on electronic states in QDs are discussed.

Dynamics and Quantum Leakage of InAs/GaAs Double Quantum Dots under Finite Time-Dependent Square-Pulsed Electric Field

2015 ◽  
Vol 1131 ◽  
pp. 97-105
Author(s):  
Aniwat Kesorn ◽  
Worasak Sukkabot ◽  
Sujin Suwanna
Keyword(s):  
Quantum Dots ◽  
Electric Field ◽  
Transition Probability ◽  
Constant Electric Field ◽  
Tight Binding ◽  
Pulsed Electric Field ◽  
Double Quantum ◽  
Contour Plot ◽  
Bloch Sphere ◽  
Double Quantum Dots

We investigate the dynamics and quantum leakage of InAs double quantum dots under the influence of a finite number of square-pulsed electric field whose amplitude varies from −0.3 to 0.3 [mV/A°]. The quantum dots are created to have identical pyramid shape with a square base of length 60.6 [A°] and height 30.3 [A°], and separated by 12.1 [A°]. Such the double quantum dots are proposed as a qubit within the given number of sequent pulses and amplitudes. The investigation consists of two parts: (i) simulations with a tight-binding theory [1] to calculate wavefunctions at constant electric field, and (ii) modeling of a two-level quantum system to calculate the state dynamics on the Bloch sphere [2] using parameters obtained from part (i). Results from part (i) give us wavefunctions under one pulse of constant electric field. After solving equations to match the wavefunctions at each pulse’s boundary, we compute the charge density as a function of times to display the quantum transition from one dot to another. This transition, its probability, and the dynamics on the Bloch sphere can be depicted with the electric field as time increases. For comparison purposes, we find that the dynamics in part (i) does not always lie in the eigenbasis, resulting in the transition probability smaller than that calculated in part (ii). Generally, the probability profiles from both parts are consistent in shape and critical points. For quantum leakage, we obtain a contour plot of the leakage as a function of the number of pulses and amplitudes, which shows that the leakage increases nonlinearly as the number of pulses and amplitude increase. Some pulses seem to induce more leakage than others, depending on the quantum state of the dots when such pulses arrive.

Tuning Optoelectronic Properties of Double Quantum Dot Structure Using Tight-Binding Model for Photo-Electric Applications

2021 ◽  
Vol 19 (3) ◽  
pp. 01-10
Author(s):  
Alaa Ayad K. Al-mebir ◽  
Shakir A.A. AL-Saidi
Keyword(s):  
Quantum Dots ◽  
Low Cost ◽  
Tight Binding ◽  
Tunneling Current ◽  
Building Blocks ◽  
Optoelectronic Properties ◽  
Double Quantum ◽  
Binding Model ◽  
Design And Synthesis ◽  
Potential Applications

In electronics field, researchers and industries have been working to fabricate low-cost optoelectronic devices by using less materials in the fabrication process. Thus, miniaturization concept has been used in the design and synthesis of the fabricated materials and devices based on nano-dimension. However, reducing the used materials would affects the overall performance of the devices and new building blocks materials are needed to pass the performance capacity limits of current silicon-based materials. Quantum Dots DQs have been introduced and attracted much attention among researchers because of their unique characteristics that are necessary for many potential applications by using nano-dimensions structures. These properties include size-tunable optical and other electronic characteristics that are not found in the current bulk materials. Although there has been interested QDs experimental studied that have been already carried out, different theoretical efforts must be introduced in order to provide good understanding of the possible and different QDs applications. In this work, therefore, optoelectronic properties of Double Quantum Dots DQDs system were studied theoretically to provide important information about the possibility of using this system in photoelectric applications. A tight-binding framework was adopted to describe the system, and all the calculations were carried out based on the steady state formalism. The proposed DQD structure was connected to metallic leads and studied to investigate the QD size dependent. The transmission calculation presented first through the electron transport mechanism. Tunneling current and conductance were then presented to provide general understanding about the behavior of the proposed system. A correlation of transmission, current and conductance results with QD radius R, incident photon energy Eph, Temperature and bias voltage have been identified. Therefore, this correlation is strongly supporting the proposal of using DQD system in fabricating nanoscale photovoltaic devices, particularly, solar cells.

Edge states, band structure, and the Hall effect in two-dimensional lattice structures: quantum dot arrays and the tight-binding model

1995 ◽  
Vol 73 (3-4) ◽  
pp. 147-162 ◽  
Author(s):  
R. Akis ◽  
C. Barnes ◽  
G. Kirczenow
Keyword(s):  
Quantum Dots ◽  
Tight Binding ◽  
Transmission Probability ◽  
Edge State ◽  
Matrix Formalism ◽  
Two Dimensional ◽  
Tight Binding Model ◽  
Edge States ◽  
Binding Model ◽  
Hall Conductance

Using a model that is based on a transfer matrix formalism, we study the electronic structure and transport in two dimensional periodic arrays of quantum dots in magnetic fields. The quantum dots in our model are connected to each other via ballistic constrictions. The spectrum for this system has much in common with that with the tight-binding model. In particular, q bulk bands arise if the normalized magnetic flux per unit cell is p/q, where p and q are coprime integers. Working within an edge-state picture, we investigate if these similarities translate to a correspondence in the transport properties of the two systems. As we shall show, the answer to this question depends very much on the transmission probability of the constrictions. Our analysis also shows that, under certain circumstances, the Hall conductance within the context of the tight-binding model may take on fractional values.

scholarly journals Interacting holes in Si and Ge double quantum dots: From a multiband approach to an effective-spin picture

2021 ◽  
Vol 104 (3) ◽  
Author(s):  
Andrea Secchi ◽  
Laura Bellentani ◽  
Andrea Bertoni ◽  
Filippo Troiani
Keyword(s):  
Quantum Dots ◽  
Double Quantum ◽  
Effective Spin ◽  
Double Quantum Dots
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