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

Abstract

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.

arXiv comment13 pages, 9 figures. To appear in Phys. Rev. B

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Cited by in corpus (14)

• Quantum Simulation of the Hubbard Model with Dopant Atoms in Silicon
• Spin-orbit coupling and anisotropic exchange in two-electron double quantum dots
• Few-electron molecular states and their transitions in a single InAs quantum dot molecule
• Charged excitons and biexcitons in laterally coupled InGaAs quantum dots
• Impurity Effects in Two-Electron Coupled Quantum Dots: Entanglement Modulation
• Suppression of charge noise using barrier control of a singlet-triplet qubit
• Leakage and sweet spots in triple-quantum-dot spin qubits: A molecular-orbital study
• Electronic structures of (In,Ga)As/GaAs quantum dot molecules made of dots with dissimilar sizes
• The Spin Density Matrix II: Application to a system of two quantum dots
• Energy spectrum, exchange interaction and gate crosstalk in a pair of double-quantum-dot system: a molecular orbital calculation
• On the validity of microscopic calculations of double-quantum-dot spin qubits based on Fock-Darwin states
• The Spin Density Matrix I: General Theory and Exact Master Equations
• Efficient Random Phase Approximation for Diradicals
• Determination of electron-hole correlation length in CdSe quantum dots using explicitly correlated two-particle cumulant