Voltage-controlled coded qubit based on electron spin

We design and analyze a solid-state qubit based on the electron spin and controlled by electrical means. The coded qubit is composed of a three-electron complex in three tunable gated quantum dots. The two logical states of a qubit, vertical bar 0L > and vertical bar 1L >, reside in a degenerate subspace of total spin S = 1/2 states. We demonstrate how applying voltages to specific gates changes the one-electron properties of the structure, and show how electron-electron interaction translates these changes into the manipulation of the two lowest energy states of the three-electron complex. (c) 2005 Elsevier Ltd. All rights reserved.