Abstract

For quantum information processing, physical implementations of qubits are needed that exhibit long coherence times but can be manipulated quickly. Promising candidates for qubits are spins of valence band holes confined to self-assembled quantum dots.

We studied an n-i semiconductor heterostructure with InGaAs self-assembled quantum dots and an AlGaAs blocking barrier as a hole storage device. Macroscopic large-area photocurrent and photoluminescence measurements are used to probe the bandstructure and potential distribution in the heterostructure, which are in good agreement with current-Poisson simulations. A fast and scalable technique is used to locate the quantum dots and determine their emission wavelengths. Measurements on single quantum dots demonstrate deterministic charging with holes. Electron and hole tunneling rates are measured and well described by one-dimensional Wentzel-Kramers-Brillouin calculations. The effect of the AlGaAs barrier on the hole tunneling rate is pointed out.