Macroscopic jumps of the axial angular momentum variance of a bidimensionally trapped ion

The time evolution of the axial angular momentum [Lcirc] z of an ion confined in a bidimensional trap is investigated. We find that, under suitable initial conditions, the interaction of the ion with two properly configured classical laser beams induces a peculiar dynamical behaviour of the axial angular momentum fluctuations. We show, in fact, that there exists an instant of time at which the variance of [Lcirc] z undergoes variations proportional to N 2 further to a change of one quantum only in the initial total number N 1 of vibrational quanta. The non-classical origin of these macroscopic jumps is brought to the light and carefully discussed.