ENERGY BALANCE IN QUANTUM MEASUREMENT

Abstract

This thesis aims to study the energy distribution over the system of interest in a process of spin-dependent interaction, which can be used to describe the measurement on the spin with the formalism of the Von Neumann measurement model. To study this problem, a time-independent model that is generalized from the Stern-Gerlach experiment is proposed and analyzed numerically. Without the presence of the spin energy, the evolution of a given initial state shows that either a weak or strong measurement can be performed in this model. However, the energy of the spin is not affected during the interaction process. To have the spin involving in the energy balance, the presence of the spin energy is necessary. Nevertheless, a clear measurement on the spin cannot be performed in this case. Consequently, it is not possible to measure the spin and to change its energy simultaneously.