The particle decay problem in the random-set approach leads naturally
to the q-Poisson distribution. Motivated by the fact that in the class
ical quantum mechanical description of particle decay one ends up with
a composite system, we construct a Hilbert space using the eigenstate
s of the average particle number operator N. In this approach, time is
represented by integer multiples of an observation quantum tau. It is
shown that these considerations lead to the redefined q-oscillator an
d an element of SUq(n) acts like a reversal operator on n time-ordered
states.