Method for Full Bloch-Sphere Control of a Localized Spin via a Single Electrical Gate

Manipulating individual spins in semiconductors requires quickly and coherently reorienting localized spins while leaving neighboring spins unaffected. Difficulties confining oscillating magnetic fields have motivated alternate approaches that use electric fields to change the local magnetic environment, including moving an electron within a hyperfine field gradient or fringe-field gradient. Higher temperatures require spins to be localized in much smaller quantum dots, however, where these techniques are less effective. In contrast, g tensor manipulation techniques couple an electric field to the spin via the spin-orbit interaction, and should be scalable to small dots with strong confinement. We describe a device design which permits coherent, non-resonant manipulation of a single electron spin to point in any direction using only a static magnetic field and a single vertical electrical gate.