Semiconductor nano devices whose operation derives from the bound states of individual dopants have received considerable attention because of the promise for new functionalities in quantum electronics.Silicon offers a particularly interesting platform for single dopants because when isotopically purified,silicon acts as a "semiconductor vacuum" for spin,giving it extraordinary coherence.Towards the goal of realising quantum electronics in silicon,controlled access to electron and nuclear spin states of phosphorous donors has recently been demonstrated.Although more difficult in silicon,optical control of single qubits is very attractive since it allows for precision quantum control with ultrahigh spectral resolution,and could enable long distance communication.