Single spin-qubit rotators based on nanojunctions: A semiclassical path integral approach

We employ a path integral semiclassical approach to compute the properties for electrons transported across quantum nanojunctions and with Rashba spin–orbit interaction (SOI). We use a piecewise semiclassical approximation for the particle orbital motion and solve the spin dynamics exactly by formulating a semiclassical theory for low dimensional systems with SOI. We obtain analytical results that can be compared with the calculations made by using the quantum waveguide approach.The proposed devices, with Π and T geometry, can be analyzed within the scope both of spin filtering and spin rotation. In fact some devices action results in a transformation of the qubit state carried by the spin, i.e. act as one-qubit spintronic quantum gates whose properties can be varied by tuning the strength of the SOI or by changing the geometrical and physical parameters in the experimentally feasible range.