Conversion of thermal equilibrium states into superpositions of macroscopically distinct states

A simple procedure for obtaining superpositions of macroscopically distinct states is proposed and analyzed. We find that a thermal equilibrium state can be converted into such a state when a single global measurement of a macroscopic observable, such as the total magnetization, is made. This method is valid for systems with macroscopic degrees of freedom and finite (including zero) temperature. The superposition state is obtained with a high (low) probability when the measurement is made with a high (low) resolution. We find that this method is feasible in an experiment.