In this article we present the results of our investigations on the ground
and the first excited states of a polaron in a polar semiconductor quantum
dot in both two and three dimensions. We have also discussed the stability
of a strong-coupling bipolaron in quantum dots. We have shown that below a
critical value of the confinement length the bipolaron becomes unstable in
a quantum dot and breaks up into two individual polarons. We have finally s
hown that the phonon-induced Zeeman splitting of the first excited level of
a two-dimensional parabolic quantum dot becomes strongly size dependent be
low a certain size and decreases very rapidly with decreasing dot size.