Random spin-orbit gates in the system of a topological insulator and a quantum dot

Abstract

The spin-dependent scattering process in a system of a topological insulator and a quantum dot is studied. The unitary scattering process is viewed as a gate transformation applied to an initial state of two electrons. Due to the randomness imposed through the impurities and alloying-induced effects of band parameters, the formalism of the random unitary gates is implemented. For quantifying entanglement in the system, we explored concurrence and ensemble-averaged R\'enyi entropy. We found that an applied external magnetic field leads to long-range entanglement on distances much larger than the confinement length. We showed that topological features of itinerant electrons sustain the formation of robust long-distance entanglement, which survives even in the presence of strong disorder.