arXiv subjects

G. Bahir

Publications and source records attributed to G. Bahir.

3 recordsLinked to original sources

arXiv2016

Controlling the Dark Exciton Spin Eigenstates by External Magnetic Field

We study the dark exciton's behavior as a coherent physical two-level spin system (qubit) using an external magnetic field in the Faraday configuration. Our studies are based on polarization-sensitive intensity autocorrelation measurements of the optical transition resulting from the recombination of a spin-blockaded biexciton state, which heralds the dark exciton and its spin state. We demonstrate control over the dark exciton eigenstates without degrading its decoherence time. Our observations agree well with computational predictions based on a master equation model.

quant-ph↗

arXiv2002

Formation of InAs Self-Assembled Quantum Rings on InP

Shape transformations of partially capped self-assembled InAs quantum dots grown on InP are studied. Atomic force microscopy images show large anisotropic redistribution of the island material after coverage by a 1 nm thick InP layer. The anisotropic material redistribution occurs within a few minutes and leads to a change from lens-like to elongated ring-like islands. The shape transformation is not accompanied by dot material compositional change. The formation of InAs/InP quantum rings disagrees with a previous model of InAs/GaAs ring formation that assumes that the driving force for the dot to ring transformation is the difference in surface diffusion velocity of indium and gallium atoms.

cond-mat↗

arXiv2002

Ultrasmall In(Ga)As Quantum Dots Grown on Strained GaxIn1-xP Layers

InAs self-assembled quantum dots were grown on strained layers of GaxIn1-xP (0 < x < 0.3) on InP substrates. We show that the quantum dots have narrow vertical dimensions, ranging between 2 to 10 monolayers only. The dot layer photoluminescence spectrum is composed of distinct spectral peaks, resulting from the discrete distribution of the dot heights. The dot height distribution depends on the total amount of InAs deposited and on the Ga content of the strained GaxIn1-xP layer underneath. Our experimental results are corroborated by an 8 band k(dot)P model calculations. In particular, we identify and quantify the diffusion of Ga from the GaxIn1-xP layer into the quantum dots.

cond-mat↗