Embodiments of the present invention are directed toward the field of spintronics, and in particular, systems and devices capable of performing spin coherent quantum logic operations. The inventive spin valve comprises two ferromagnetic electrode layers, and a non-magnetic conducting layer positioned therebetween. An external magnetic field {right arrow over (B)}.sub.0 is applied in the Z direction, such that the two electrode layers are each magnetized in a direction substantially parallel to the external magnetic field. Rather than attempting to change the magnetization of one of the ferromagnetic layers, as is the case in prior art technologies, it is the direction of the electron spin that is manipulated in the present embodiments while the electron is traveling through the middle, nonmagnetic layer. One of the ferromagnetic electrodes may be the tip of a scanning tunneling microscope (STM). This configuration may further comprise a bias voltage source connected between the STM tip and the other ferromagnetic electrode, such that a spin polarized tunneling current is conducted between the two.