Coherent charge oscillation in a semiconductor double quantum dot

The time evolution of a pulse-excited charge qubit in a semiconductor double quantum dot is investigated. All-electrical initialization and coherent gate control of the system are achieved, and coherent charge oscillation is observed through the transport measurements. The oscillation frequency and decoherence time T/sub 2/ are estimated by fitting the transport data with a simple model. Possible decoherence mechanisms in a charge qubit system are pointed out and discussed in detail.