Gabriel Bester

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Self-assembled quantum dots are often modeled by continuum models seffective mass or k ·pd that assume the symmetry of the dot to be that of its overall geometric shape. Lens-shaped or conical dots are thus assumed to have continuous cylindrical symmetry C`v, whereas pyramidal dots are assumed to have C4v symmetry. However, considering that the III–V dots(More)
We predict that heterostructure quantum wires and [111] grown quantum dots have a vanishing fine-structure splitting on the grounds of their symmetry, and are therefore ideal candidates to generate entangled photon pairs. We underpin this proposal by atomistic million-atom many-body pseudopotential calculations of realistic structures and find that the(More)
The existence of enormous strain fields in self-assembled quantum dots has led to the expectation of dramatic effects of piezoelectricity. However, only linear piezoelectric tensors were used in all previous calculations. We calculate the piezoelectric properties of self-assembled quantum dots using the linear and quadratic piezoelectric tensors derived(More)
We show that the piezoelectric effect that describes the emergence of an electric field in response to a crystal deformation in III-V semiconductors such as GaAs and InAs has strong contributions from second-order effects that have been neglected so far. We calculate the second-order piezoelectric tensors using density-functional theory and obtain the(More)
G. Bester,1 D. Reuter,2 Lixin He,1 A. Zunger,1 P. Kailuweit,2 A. D. Wieck,2 U. Zeitler,3 J. C. Maan,3 O. Wibbelhoff,4 and A. Lorke4 1National Renewable Energy Laboratory, Golden, Colorado 80401, USA 2Ruhr-Universität, 44801 Bochum, Germany 3High Field Magnet Laboratory, 6525 ED Nijmegen, The Netherlands 4Universität Duisburg-Essen, 47048 Duisburg, Germany(More)
Long-term sustainable management of zebra chip (ZC) disease of potato requires development of tolerant or resistant germplasm. To this end, 283 potato varieties and breeding clones were infected with the ZC putative causal agent 'Candidatus Liberibacter solanacearum' (Lso) by potato psyllid vector inoculations in 2010, 2011, 2012, and 2013. Potato germplasm(More)
The potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), and its associated pathogen "Candidatus Liberibacter solanacearum" (Ca. L. solanacearum), the putative causal agent of zebra chip (ZC) disease in potatoes (Solanum tuberosum L.), were sampled in commercial potato fields and untreated control plots for 3 yr in multiple locations in(More)
We study the effect of an external biaxial stress on the light emission of single InGaAs/GaAs(001) quantum dots placed onto piezoelectric actuators. With increasing compression, the emission blueshifts and the binding energies of the positive trion (X+) and biexciton (XX) relative to the neutral exciton (X) show a monotonic increase. This phenomenon is(More)
Neat liquid phosphoric acid (H(3)PO(4)) has the highest intrinsic proton conductivity of any known substance and is a useful model for understanding proton transport in other phosphate-based systems in biology and clean energy technologies. Here, we present an ab initio molecular dynamics study that reveals, for the first time, the microscopic mechanism of(More)
We present a pseudopotential calculation of the single particle and excitonic spectrum of CdSe nanocrystals. We find that in the excitonic manifold derived from the ground state electron and the first 60 hole states there are two energy gaps much larger than the typical LO phonon energy in bulk CdSe. Such gaps can effectively slow down the hole relaxation(More)