Measurement of a single electron spin in a solid state quantum computer

Abstract

A spin state of an electron in a quantum dot (quantum bit) could be tested by a spin-polarized current passing through the narrow constriction in a quantum wire placed near the dot. A fairly strong tunnel coupling between the quantum dot and the constriction is required to enhance an exchange interaction. Charge related phenomena such as a charge blockade and single electron flow through the narrow constriction are examined. The conditions when a spin blockade dominates are revealed.