A quantum dot spin injector with spin bias.

We propose a spin injector consisting of a quantum dot (QD), which is coupled to two leads, to separate either spin-up or spin-down electrons from one lead into the other. Meanwhile, a single electron spin state can also be written into the QD. It works mainly due to the spin bias in one of the leads, which has been realized in recent experiments by Frolov et al. [Phys. Rev. Lett. 102, 116802 (2009); Nature (London) 458, 868 (2009)], and the Coulomb blockade effect in the QD. This device is realizable with current technologies and may have practical use in spintronics or quantum processing. [ABSTRACT FROM AUTHOR]