  Designing coherent processes is essential for developing quantum information
technologies. We study coherent dynamics of two spatially separated electrons
in a coupled semiconductor double quantum dot (DQD), in which various two-qubit
operations are demonstrated just by adjusting the gate voltages. Especially,
second-order correlated coherent oscillations provide functional quantum
processes for making quantum correlation of separated particles. The results
encourage searching quantum entanglement in electronic devices.
