Spintronic single-qubit gate based on a quantum ring with spin-orbit interaction -: art. no. 033309

In a quantum ring connected with two external leads, the spin properties of an incoming electron are modified by the spin-orbit interaction, resulting in a transformation of the qubit state carried by the spin. The ring acts as a one-qubit spintronic quantum gate whose properties can be varied by tuning the Rashba parameter of the spin-orbit interaction, by changing the relative position of the junctions, as well as by the size of the ring. We show that a large class of unitary transformations can be attained with already one ring-or a few rings in series-including the important cases of the Z, X, and Hadamard gates. By choosing appropriate parameters the spin transformations can be made unitary, which corresponds to lossless gates.