New scheme of spin qubits driven by ac electric field

A new scheme of spin qubit with a quantum dot under a slanting Zeeman field is proposed. The qubit is defined as a hybrid orbital and spin state, and referred as quasi-spin qubit. The quasi-spin rotation is performed by letting an electron in a quantum dot to oscillate in a stray field generated by micro-magnets. Numerical calculation of the stray field shows that the resultant slanting Zeeman field can be large enough for realizing a sub 100 ns pi-rotation for a realistic design of a lateral quantum dot.