Conversion of equilibrium spin current into charge current through a quantum-dot spin valve subject to circularly polarized field

• Equilibrium spin current can be converted to charge current with polarized light.
• The equilibrium spin current can be deduced from the induced charge current.
• The induced charge current is measurable in experiments.

We theoretically investigate the electron transport through a quantum-dot spin valve subject to a circularly polarized field. It is shown that the original equilibrium spin current arising from the spin Josephson effect can be converted to a charge current by the circularly polarized field. Numerical calculations demonstrate that the sign and the magnitude of the equilibrium spin current can both be deduced from the induced charge current. Moreover, the dependence of the induced charge current on the system parameters is also studied and the most important finding is that for most choices of the system parameters the induced charge current is large enough to be measured by present technology. Therefore, our findings offer a promising way to detect the equilibrium spin current in spin valve systems.