Spintronics is a multidisciplinary field whose central theme is the active manipulation of spin degrees of freedom in solid-state systems. Besides being useful in contemporary technology, spintronics may also contribute to the field of quantum computation and quantum information, in which spin-1/2 is a natural candidate for the quantum bit (qubit) realization. To this end, one should be able to write and read quantum information on a spin-1/2 system. These operations are equivalent to polarizing the spin along a specific direction (writing) and identifying the direction along which the spin is polarized (reading). Recently, we proposed a perfect spin filter based on a diamond-shaped mesoscopic interfetometer, which is subject to both an Aharonov-Bohm flux (which can be tuned by an external magnetic field) and spin-orbit interactions (which can be tuned by external gate voltages) [1].

In this talk, I will present a model which demonstrates the robustness of such spin filters against current leakage out of the interferometer, which exists in practical situations [2]. In addition, I will present a similar proposal for a spin filter based on a double-dot interferometer [3]. The advantages of this spin filter over our previously suggested diamond interferometer will be discussed.