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

The time evolution of the axial angular momentum (L) over cap (z) of an ion confined in a bidimensional trap is investigated. We find that, under suit able initial conditions, the interaction of the ion with two properly confi gured classical laser beams induces a peculiar dynamical behaviour of the a xial angular momentum fluctuations. We show, in fact, that there exists an instant of time at which the variance of (L) over cap (z) undergoes variati ons proportional to N-2 further to a change of one quantum only in the init ial total number N much greater than1 of vibrational quanta. The non-classi cal origin of these macroscopic jumps is brought to the light and carefully discussed.