  Antihydrogen atoms are produced at CERN in highly excited Rydberg states.
However, precision measurements require anti-atoms in ground state. Whereas
experiments currently rely on spontaneous emission only, simulations have shown
that THz light can be used to stimulate the decay towards ground state and thus
increase the number of anti-atoms available for measurements. We review
different possibilities at hand to generate light in the THz range required for
the purpose of stimulated deexcitation. We demonstrate the effect of a
blackbody type light source, which however presents drawbacks for this
application including strong photoionization. Further, we report on the first
THz transitions in a beam of Rydberg caesium atoms induced by photomixers and
conclude with the implications of the results for the antihydrogen case.
