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.