  We analyze the quantum dynamics of a two-level emitter in a resonant
microcavity with optical feedback provided by a distant mirror (i.e., a
half-cavity) with a focus on stabilizing the emitter-microcavity subsystem. Our
treatment is fully carried out in the framework of cavity quantum
electrodynamics. Specifically, we focus on the dynamics of a perturbed dark
state of the emitter to ascertain its stability (existence of time oscillatory
solutions around the candidate state) or lack thereof. In particular, we find
conditions under which multiple feedback modes of the half cavity contribute to
the stability, showing certain analogies with the Lang-Kobayashi equations,
which describe a laser diode subject to classical optical feedback.
