Semiconductor few-electron quantum dots as spin qubits

Abstract

The experimental steps taken towards using the spin of a single electron trapped in a semiconductor quantum dot as a spin qubit1 is described. Fabrication and characterization of a double quantum dot containing two coupled spins has been achieved, as well as initialization and single-shot read-out of the spin state. The single-spin relaxation time was found to be of the order of a millisecond, but the decoherence time is still unknown. Concrete ideas-using a charge detection approach-on how to proceed towards demonstrating superposition and entanglement of spin states are presented. Single-spin manipulation relies on a microfabricated wire located close to the quantum dot, and two-spin interactions are controlled via the tunnel barrier connecting the respective quantum dots. © 2006 Springer Science+Business Media, Inc.