  We present a microscopic theory of a lateral quantum dot molecule in a radial
magnetic field with a Greenberger- Horne- Zeilinger (GHZ) maximally entangled
three particle groundstate. The quantum dot molecule consists of three quantum
dots with one electron spin each forming a central equilateral triangle. The
anti-ferromagnetic spin-spin interaction is changed to the ferromagnetic
interaction by additional doubly occupied quantum dots, one dot near each side
of a triangle. The magnetic field is provided by micro-magnets. The interaction
among the electrons is described within an extended Hubbard Hamiltonian and
electronic states are obtained using configuration interaction approach. The
set of parameters is established for which the ground state of the molecule in
a radial magnetic field is well approximated by a GHZ state.
