  Antihydrogen atoms are routinely formed at the Antiproton Decelerator at CERN
in a wide range of Rydberg states. To perform precision measurements,
experiments rely on ground state antimatter atoms which are currently obtained
only after spontaneous decay. In order to enhance the number of atoms in ground
state, we propose and assess the efficiency of different methods to stimulate
their decay. First, we investigate the use of THz radiation to simultaneously
couple all n-manifolds down to a low lying one with sufficiently fast
spontaneous emission toward ground state. We further study a deexcitation
scheme relying on state-mixing via microwave and/or THz light and a coupled
(visible) deexcitation laser. We obtain close to unity ground state fractions
within a few tens of microseconds for a population initiated in the n=30
manifold. Finally, we study how the production of antihydrogen atoms via
stimulated radiative recombination can favourably change the initial
distribution of states and improve the overall number of ground-state atoms
when combined with the stimulated deexcitation proposed.
