Effects of impurity on the ground-state transitions of a quantum dot in strong magnetic field

The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated. While it has been known that the electron- electron interaction leads to ground-state transitions on magic Values of a ngular momentum in a magnetic field. We show, in this paper, that the impla ntation of an impurity ion at the center can either enhance or suppress suc h transitions, depending on whether it is an acceptor or a donor ion.