Electron spin qubits in quantum dots

We review our experimental progress on the spintronics proposal for quantum computing where the quantum bits (qubits) are implemented with electron spins confined in semiconductor quantum dots. Out of the five criteria for a scalable quantum computer, three have already been satisfied. We have fabricated and characterized a double quantum dot circuit with an integrated electrometer. The dots can be tuned to contain a single electron each. We have resolved the two basis states of the qubit by electron transport measurements. Furthermore, initialization and single-shot read-out of the spin state have been achieved. The single-spin relaxation time was found to be very long, but the decoherence time is still unknown. We present concrete ideas on how to proceed towards coherent spin operations and two-qubit operations.