Numerical study of spin effects in single and double quantum dots

Tamura, Hiroyuki

doi:10.1016/s0921-4526(98)00100-8

Cited by 33 publications

(19 citation statements)

References 8 publications

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“…The central approximation used almost universally is that the single-particle physics is treated via particle-in-a-box effective-mass approximation (EMA), where multi-band and intervally couplings are neglected. (In this work, we will deviate from this tradition, see below) Many-body treatments of this simplified EMA model range from phenomenological Hubbard 9 or Heisenberg 5,9 models using empirical input parameters, to microscopic Hartree-Fock (HF) 10,11,12 , local spin densities (LSD) approximation 13,14 and configuration interaction (CI) method.…”

Section: Two Verticallymentioning

confidence: 99%

“…We calculate first the singlet-triplet splitting vs inter-dot separation, finding the singlet to be below the triplet. We then simplify our model in successive steps, reducing the sophistication with which interelectronic correlation is described and showing how these previously practiced approximations 10,11,12,13,14 lead to different values of J S−T , including its sign reversal. This methodology provides insight into the electronic processes which control the singlettriplet splitting in dot-molecules.…”

Section: 15mentioning

confidence: 99%

“…Given that RHF and LSD are widely used in studying QMDs, 10,13,14 it is important to understand under which circumstance the methods will succeed and under which circumstance they will fail in describing the few-electron states in a QDM. In level-3 theory, we thus mimic the mean-field theory by further ignoring the off-diagonal Coulomb integrals in Eq.…”

Section: B Level-2 Theory: Reduced CI In the Molecular Basismentioning

confidence: 99%

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Singlet-triplet splitting, correlation, and entanglement of two electrons in quantum dot molecules

Bester

Zunger

2005

Phys. Rev. B

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Starting with an accurate pseudopotential description of the single-particle states, and following by configuration-interaction treatment of correlated electrons in vertically coupled, self-assembled InAs/GaAs quantum dot-molecules, we show how simpler, popularly-practiced approximations, depict the basic physical characteristics including the singlet-triplet splitting, degree of entanglement (DOE) and correlation. The mean-field-like single-configuration approaches such as Hartree-Fock and local spin density, lacking correlation, incorrectly identify the ground state symmetry and give inaccurate values for the singlet-triplet splitting and the DOE. The Hubbard model gives qualitatively correct results for the ground state symmetry and singlet-triplet splitting, but produces significant errors in the DOE because it ignores the fact that the strain is asymmetric even if the dots within a molecule are identical. Finally, the Heisenberg model gives qualitatively correct ground state symmetry and singlet-triplet splitting only for rather large inter-dot separations, but it greatly overestimates the DOE as a consequence of ignoring the electron double occupancy effect.

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Section: Two Verticallymentioning

confidence: 99%

Section: 15mentioning

confidence: 99%

Section: B Level-2 Theory: Reduced CI In the Molecular Basismentioning

confidence: 99%

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Singlet-triplet splitting, correlation, and entanglement of two electrons in quantum dot molecules

Bester

Zunger

2005

Phys. Rev. B

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“…Thus, the value of ⌬ SAS relative to ប 0 will have a dramatic effect on the electronic properties of QM's . [7][8][9][10][12][13][14] For small-N values, ប 0 is often taken to be N-independent. We ourselves have indeed previously employed such a N-independent ប 0 in such cases.…”

Section: Main Analytical Method: Local-spin Density-functional Tmentioning

confidence: 99%

“…Artificial quantum molecules (QM's) composed of two vertically coupled semiconductor QD's are the subject of much experimental and theoretical investigation. [3][4][5][6][7][8][9][10][11][12][13][14][15] In this paper we discuss integer filling factor phases that appear in vertical QM's that have different values for the thickness b of the central barrier separating the two QD's when a magnetic field ͑B ʈ ͒ is applied parallel to the drain current I d flowing through the two QD's (see schematic of the submicron circular mesa in the Fig. 1 inset).…”

Section: Introductionmentioning

confidence: 99%

Integer filling factor phases and isospin in vertical diatomic artificial molecules

et al. 2004

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Integer filling factor phases of many-electron vertically coupled diatomic artificial quantum dot molecules are investigated for different values of the interdot coupling. The experimental results are analyzed within local-spin density functional theory for which we have determined a simple lateral confining potential law that can be scaled for the different coupling regimes, and Hartree-Fock theory. Maximum density droplets composed of electrons in both bonding and antibonding or just bonding states are revealed, and interesting isospinflip physics appears for weak interdot coupling when the systematic depopulation of antibonding states leads to changes in isospin.

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Spin-Orbit Energy State Splitting in Semiconductor Cylindrical and Spherical Quantum Dots

Voskoboynikov

Lee

Tretyak

2001

phys. stat. sol. (b)

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We present a theoretical study of the spin-orbit interaction impact on electron energy states in small cylindrical and spherical quantum dots. The investigation is based on the effective one-electronic band Hamiltonian and the spin dependent boundary conditions. It has been demonstrated that the spin-orbit interaction can significantly modify the energy spectrum of InAs and InSb quantum dots. The splitting can provide a situation where only the lowest spin split energy states are bound in the dot. A reasonable agreement was found with data from more sophisticated theoretical models for the spherical quantum dots which is available in the literature.

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Numerical study of spin effects in single and double quantum dots

Cited by 33 publications

References 8 publications

Singlet-triplet splitting, correlation, and entanglement of two electrons in quantum dot molecules

Singlet-triplet splitting, correlation, and entanglement of two electrons in quantum dot molecules

Integer filling factor phases and isospin in vertical diatomic artificial molecules

Spin-Orbit Energy State Splitting in Semiconductor Cylindrical and Spherical Quantum Dots

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