Abstract: A method for laterally confining neutral excitons in a semiconductor layer structure (11) of a solid-state device comprises creating an inhomogeneous electric field (F) in the semiconductor layer structure (11), the electric field (F) having an in-plane field component (Fx) whose magnitude varies along at least at least one confinement direction (x) in the device plane, the magnitude of the in-plane field component (Fx) having a maximum along the confinement direction (x). In this manner a lateral confining potential (V(x)) for neutral excitons is caused around the maximum. The solid-state device (10) is irradiated with light to create neutral excitons in the semiconductor layer structure (11). The neutral excitons are laterally confined along the confinement direction (x) by the lateral confining potential (V(x)).

Abstract: A quantum computer is proposed in which information is stored in the two lowest electronic states of doped quantum dots. Multiple quantum dots are located in a microcavity, and a pair of gates controls the energy levels in each quantum dot. A controlled NOT (CNOT) operations involving any pair of quantum dots can be effected by a sequence of gate voltage pulses which tune the quantum dot energy levels into resonance with frequencies of the cavity or a laser. The duration of a CNOT operation is estimated to be much shorter than the time for an electron to decohere by emitting an acoustic phonon.