ИСТИНА

We have considered relativistic fluxon dynamics governed by the sine-Gordon equation and affected by short spatial inhomogeneities of the driving force and thermal noise. Developed analytical and numerical methods for calculation of fluxon scattering at the inhomogeneities allowed us to examine the scattering as a measurement tool for sensitive detection of superconducting flux qubit states. Different measurement schemes based on the scattering were optimized for signal-to-noise ratio maximization. The scattering was also considered as a tool for manipulation with the qubit states. Analysis of this type of manipulations with qubit states was performed in the frame of fully quantum description both analytically and numerically. In terms of the simplest model of two-level system with magnetic moment we analyzed the possibility of fast magnetization reversal on the picosecond timescale induced by unipolar magnetic pulse. In addition, consideration of the magnetization reversal is fulfilled in the framework of the macroscopic theory of the magnetic moment allowing the comparison and the explanation of quantum and classical behavior.