Measuring mesoscopic spin currents by spin-to-charge conversion

A number of theoretical investigations show that spin currents can be magneto-electrically generated by passing electric currents through spin-orbit coupled quantum dots. Measuring these currents has however not been achieved to date. In this talk, we present a theoretical proposal for measuring such mesoscopic spin currents with a voltage probe connected to the quantum dot via a single channel quantum point contact. We demonstrate that a spin current flowing through the quantum point contact results in an odd dependence of the charge current $I_{\rm qpc}$ on an externally applied Zeeman field, while this response is even in the absence of the spin current. The magnitude of the spin current is proportional to the zero field derivative of $I_{\rm qpc}$, with a constant of proportionality depending weakly on the geometry of the point contact. Numerical estimates suggest that in this way, mesoscopic spin currents can successfully be measured in GaAs quantum dots.