  In this paper, we revisit one of the prototypical PT-symmetric oligomers,
namely the trimer. We find all the relevant branches of "regular" solutions and
analyze the bifurcations and instabilities thereof. Our work generalizes the
formulation that was proposed recently in the case of dimers for the so-called
"ghost states" of trimers, which we also identify and connect to
symmetry-breaking bifurcations from the regular states. We also examine the
dynamics of unstable trimers, as well as those of the ghost states in the
parametric regime where the latter are found to exist. Finally, we present the
current state of the art for optical experiments in PT-symmetric trimers, as
well as experimental results in a gain-loss-gain three channel waveguide
structure.
