Planar Rotor in Matrix Mechanics and the Role of States in Quantum Physics

Abstract

We illustrate Heisenberg's method of matrix mechanics using the planar quantum rotor example. We show how to find the spectrum of this simple model without the need to use the eigenstates of the system. This then leads us to speculate on the role the Heisenberg state plays in quantum mechanics and to ask whether one could even completely dispose of the need for states.