  We demonstrate a fundamental breakdown of the photonic spontaneous emission
(SE) formula derived using Fermi's golden rule, in absorptive and amplifying
media, where one assumes the SE rate scales with the local photon density of
states, an approach often used in more complex, semiclassical nanophotonics
simulations. Using a rigorous quantization of the macroscopic Maxwell equations
in the presence of arbitrary linear media, we derive a corrected Fermi's golden
rule and master equation for a quantum two-level system (TLS) yielding the
direct appearance of a quantum pumping term and a modified decay rate that is
net positive. We show rigorous numerical results of the temporal dynamics of
the TLS for an example of two coupled microdisk resonators, forming a gain-loss
medium, and demonstrate the clear failure of the semiclassical theory.
