Readout of a single electron spin based quantum bit by current detection

We present experimental and theoretical results demonstrating the readout of a single spin based quantum bit by current detection. The quantum bit has been built by isolating a single electron spin in a lateral dot with a tunable number of electrons. The spin state of the dot was read from the current amplitude resulting from the injection of spin polarized electrons. The current amplitude showed a systematic dependence on the spin state of the dot controlled by the number of electrons.