Rashba Spin-Orbit Coupling in Quantum Wire Networks

In recent years, much interest has been given to the field of quantum computing, due to its potential to solve certain problems much more efficiently than classical computational methods. A popular choice for the quantum bit of a quantum computer is the spin of a single electron. It has been shown that the spin of an electron can be manipulated through the mechanism of spin-orbit coupling. In this work we study the effect of Rashba spin-orbit coupling on electron transport through a variety of quantum structures. To do this, we use a scattering matrix formalism that allows us to calculate the evolution of the electron wave function as it propagates through the system under investigation. Three quantum geometries are considered – a straight wire, a ring structure, and a y-branching structure. In the straight wire, we observe the precession of spin-polarized electrons as they propagate through the wire. In the ring structure, interference patterns are observed in the conductance of the device, due to the accumulation of non-Abelian phase by electrons traveling on opposite sides of the ring. In the y-branching structure, we observe a spin-filtering effect, where spin-up electrons are concentrated in one output wire, and spin-down electrons are concentrated in the other output wire.