Fractional orbital occupation of spin and charge in artificial atoms

Abstract

We present results on spin and charge correlations in two-dimensional quantum dots as a function of increasing Coulomb strength (dielectric constant). We look specifically at the orbital occupation of both spin and charge. We find that charge and spin evolve separately, especially at low Coulomb strength. For the charge, we find that a hole develops in the core orbitals at strong Coulomb repulsion, invalidating the common segregation of confined electrons into an inert core and active valence electrons. For excitations, we find a total spin-projection Sz = –1/2 breaks apart into separate occupations of net positive and negative spin. This dissociation is caused by spin correlations alone. Quantum fluctuations arising from long-range Coulomb repulsion destroy the spin dissociation and eventually results in all orbitals carrying a negative spin.

Chiral spin textures of strongly interacting particles in quantum dots

“…There is evidence that such a coupling may break the degeneracy between the spin-winding states. 50 Together with the strong Coulomb repulsion present in these small quantum systems, the chiral structures that emerge should exhibit longer lifetimes and lower decoherence rates than their more conventional counterparts.…”

“…When Coulomb interactions are considered, the repulsion smears out the density over different orbital configurations. 47 The competition between repulsion and confinement results in an annular density about the origin. These interaction effects are strong; the ground-state energy of the interacting system is 10.30 meV for these experimentally-relevant system parameters-more than twice the ground-state energy of the non-interacting case (4.0 meV).…”