| 1. |
- Lu, P. F., et al.
(författare)
-
Electronic and optical properties of InGaAs/GaAs quantum dots with tunable aspect-ratio
- 2014
-
Ingår i: Modern Physics Letters B. - : World Scientific Pub Co Pte Lt. - 0217-9849 .- 1793-6640. ; 28:9
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a combined approach of finite element method (FEM) and quadratic programming optimization method is proposed to investigate the nonuniform equilibrium composition profile of InGaAs/GaAs quantum dots (QDs) in the framework of Gibbs energy optimization (GEO). The proposed QDs are varied with aspect ratio from 0.3 to 0.5. The wave functions of electron and heavy hole are predicted by using the k . p method. The changes of wave functions before and after optimization can be observed by using composition optimization. Both the eigenvalues and transition energy change obviously with the increasing aspect ratio. The linear optical absorption coefficients corresponding to the interband ground state transition are obtained via the density matrix approach and perturbation expansion method. The numerical results reveal that the aspect ratio and composition profile play significant roles in determining the electronic and optical properties.
|
|
| 2. |
- Zhang, X. L., et al.
(författare)
-
Structural and electronic properties of InPBi alloys
- 2014
-
Ingår i: Modern Physics Letters B. - : World Scientific Pub Co Pte Lt. - 0217-9849 .- 1793-6640. ; 28:17
-
Tidskriftsartikel (refereegranskat)abstract
- First-principle calculations have been performed to systematically investigate structural and electronic properties of InPBi alloys. The formation energy of seven different configurations is studied. The strength of covalent bonding largely depends on the strong s-p hybridization among In-5s, P-3p and Bi-6p states. The band gap of InPBi shrinks clearly with the increasing Bi concentration and the band edge shifts when spin-orbit coupling (SOC) is considered. The insertion of Bi atom leads to hybridization of In/P/Bi p states which contributes a lot around Fermi level. In addition, our results show that the biaxial strain is an effective method to tune the electronic properties of the system.
|
|
| 3. |
- Johannesson, Henrik, 1953, et al.
(författare)
-
Two-Impurity Kondo Model: Spin-Orbit Interactions and Entanglement
- 2011
-
Ingår i: Modern Physics Letters B. - 0217-9849. ; 25
-
Konferensbidrag (refereegranskat)abstract
- Motivated by proposals to employ RKKY-coupled spins as building blocks in a solid-state quantum computer, we analyze how the RKKY interaction in a 2D electron gas is influenced by spin-orbit interactions. Using a two-impurity Kondo model with added Dresselhaus and Rashba spin-orbit interactions we find that spin-rotational invariance of the RKKY interaction — essential for a well-controllable two-qubit gate — is restored when tuning the Rashba coupling to have the same strength as the Dresselhaus coupling. We also discuss the critical properties of the two-impurity Kondo model in the presence of spin-orbit interactions, and extract the leading correction to the block entanglement scaling due to these interactions.
|
|
| 4. |
- Mingbo, Sun, et al.
(författare)
-
A Modified Sub-Cell-Fix Method for Re-Initialization of Level-Set Distance Function and Its Dependence Tests on Grid Stretching
- 2010
-
Ingår i: Modern Physics Letters B. - 0217-9849. ; 24:15, s. 1615-1629
-
Tidskriftsartikel (refereegranskat)abstract
- The sub-cell-fix (SCF) method proposed by Russo and Smereka(3) computes the distance function of the cells adjacent to the zero level-set without disturbing the original zero level-set. A modified sub-cell-fix scheme independent of local curvature is developed in this paper, which makes use of a combination of the points adjacent to zero level-set surfaces and preserves the interface in a second-order accuracy. The new sub-cell-fix scheme is capable of handling large local curvature, and as a result it demonstrates satisfactory performance on several challenging test cases. The limitations of the modified scheme on stretched grids are tested and it is found that the highly stretched grid causes large numerical errors, and needs further assessment and modification.
|
|
