  In this work, we explore the PT-symmetric quantum Rabi model, which describes
a PT-symmetric qubit coupled to a quantized light field. By employing the
adiabatic approximation (AA), we are able to solve this model analytically in
the parameter regime of interest and analyze various physical aspects. We
investigate the static and dynamic properties of the model, using both the AA
and numerical diagonalization. Our analysis reveals a multitude of exceptional
points (EPs) that are closely connected with the exactly solvable points in the
Hermitian counterpart of the model. Intriguingly, these EPs vanish and revive
depending on the light-matter coupling strength. Furthermore, we discuss the
time evolution of physical observables under the non-Hermitian Hamiltonian.
Rich and exotic behaviors are observed in both strong and ultra-strong coupling
regimes. Our work extends the theory of PT symmetry into the full quantum
light-matter interaction regime and provides insights that can be readily
enlarged to a broad class of quantum optical systems.
