  The phenomenon of chiral-symmetry protected thermalization gap in Hermitian
photonic systems is counterintuitive as it implies that the photon coherence
can be continuously improved by disorders towards an asymptotic limit. We show
that the phenomenon disappears in time-independent, non-Hermitian photonic
systems even when the chiral symmetry is well preserved. In fact, the degree of
thermalization generally increases with the disorder strength, in agreement
with intuition. As non-Hermitian characteristics (e.g., weak gain and loss) can
be expected in realistic physical situations, the phenomenon of thermalization
gap may be observed but only in well controlled experiments with high quality
materials.
