Detection of single spin decoherence in a quantum dot via charge currents

We consider a quantum dot attached to leads in the Coulomb blockade regime that has a spin 1/2 ground state. We show that, by applying an ESR field to the dot spin, the stationary current in the sequential tunneling regime exhibits a new resonance peak whose linewidth is determined by the single spin decoherence time T-2. The Rabi oscillations of the dot spin are shown to induce coherent current oscillations from which T-2 can be deduced in the time domain. We describe a spin inverter which can be used to pump current through a double dot via spin hips generated by ESR.