Measuring current by counting electrons in a nanowire quantum dot

We measure current by counting single electrons tunneling through an InAs nanowire quantum dot (QD). The charge detector is realized by fabricating a quantum point contact in close vicinity to the nanowire. The results based on electron counting compare well to a direct measurements of the QD current, when taking the finite bandwidth of the detector into account. The ability to detect single electrons also opens up possibilities for manipulating and detecting individual spins in nanowire QDs. (C) 2008 American Institute of Physics.