Two-electron lateral quantum-dot molecules in a magnetic field

We study electronic structures of two-dimensional quantum dots in high magnetic fields using the density-functional theory (DFT) and the exact diagonalization (ED). With increasing magnetic field, beyond the formation of the totally spin-polarized maximum density droplet (MDD) state, the DFT gives the ground-state total angular momentum as a continuous function with well-defined plateaus. The plateaus agree well with the magic angular momenta of the ED calculation. By constru...

We present a thorough analysis of the electron density distribution (shape) of two electrons, confined in the three-dimensional harmonic oscillator potential, as a function of the perpendicular magnetic field.Explicit algebraic expressions are derived in terms of the system's parameters and the magnetic field strength to trace the shape transformations in the ground and low-lying excited states. We found that the interplay of the classical and quantum properties lead to a qua...

We present a theory of spin, electronic and transport properties of a few-electron lateral triangular triple quantum dot molecule in a magnetic field. Our theory is based on a generalization of a Hubbard model and the Linear Combination of Harmonic Orbitals combined with Configuration Interaction method (LCHO-CI) for arbitrary magnetic fields. The few-particle spectra obtained as a function of the magnetic field exhibit Aharonov-Bohm oscillations. As a result, by changing the...

We present a study of the electronic structure of two laterally coupled gaussian quantum dots filled with two particles. The exact diagonalization method has been used in order to inspect the spatial correlations and examine the particular spin singlet-triplet configurations for different coupling degrees between quantum dots. The outcome of our research shows this structure to have highly modifiable properties promoting it as an interesting quantum device, showing the possib...

We demonstrate the existance of ferrimagnetic and ferromagnetic phases in a spin phase diagram of coupled lateral quantum dot molecules in the quantum Hall regime. The spin phase diagram is determined from Hartree-Fock Configuration Interaction method as a function of electron numbers N, magnetic field B, Zeeman energy, and tunneling barrier height. The quantum Hall ferrimagnetic phase corresponds to spatially imbalanced spin droplets resulting from strong inter-dot coupling ...

The effects of spin-orbit coupling on the two-electron spectra in lateral coupled quantum dots are investigated analytically and numerically. It is demonstrated that in the absence of magnetic field the exchange interaction is practically unaffected by spin-orbit coupling, for any interdot coupling, boosting prospects for spin-based quantum computing. The anisotropic exchange appears at finite magnetic fields. A numerically accurate effective spin Hamiltonian for modeling spi...

We study effects of electron-electron interactions and confinement potential on the magneto-optical absorption spectrum in the far-infrared range of lateral quantum dot molecules. We calculate far-infrared (FIR) spectra for three different quantum dot molecule confinement potentials. We use accurate exact diagonalization technique for two interacting electrons and calculate dipole-transitions between two-body levels with perturbation theory. We conclude that the two-electron ...

We investigate the stability of few-electron quantum phases in vertically coupled quantum dots under a magnetic field of arbitrary strength and direction. The orbital and spin stability diagrams of realistic devices containing up to five electrons, from strong to weak inter-dot coupling, is determined. Correlation effects and realistic sample geometries are fully taken into account within the Full Configuration Interaction method. In general, the magnetic field drives the sys...

Using exact diagonalization we study the low energy Hilbert space of the two-electron, two-quantum dot artificial molecule under a perpendicular magnetic field. We show that electrons bind to vortices to induce several spin transitions among ground states. Furthermore, the lowest excited states of either even or odd vorticity mix, opening an anticrossing which protects the quantum information stored in the spin states of the strongly correlated quantum dot molecule.

Ground-state and excited-state properties of vertically coupled double quantum dots are studied by exact diagonalization. Magic-number total angular momenta that minimize the total energy are found to reflect a crossover between electron configurations dominated by intra-layer correlation and ones dominated by inter-layer correlation. The position of the crossover is governed by the strength of the inter-layer electron tunneling and magnetic field. The magic numbers should ha...