Implementing controlled-NOT gate based on free spin qubits with semiconductor quantum-dot array

Based on electron spins in semiconductor quantum dots as qubits, a new quantum controlled-NOT (CNOT) gate is constructed in solid nanostructure without resorting to spin-spin interactions. Single-electron tunneling technology and coherent quantum-dot cellular-automaton architecture are used to generate an ancillary charge entangled state. Using the ancillary charge entangled state as an intermediate state, we obtain a spin entangled state and design a CNOT gate by using only single-spin rotations.