  For the applications of the frequency comb in microresonators, it is
essential to obtain a fully frequency-stabilized microcomb laser source. Here,
we demonstrate an atom-referenced stabilized soliton microcomb generation
system based on the integrated microring resonator. The pump light around
$1560.48\,\mathrm{nm}$ locked to an ultra-low-expansion (ULE) cavity, is
frequency-doubled and referenced to the atomic transition of
$^{87}\mathrm{Rb}$. The repetition rate of the soliton microcomb is
injection-locked to an atomic-clock-stabilized radio frequency (RF) source,
leading to mHz stabilization at $1$ seconds. As a result, all comb lines have
been frequency-stabilized based on the atomic reference and could be determined
with very high precision reaching $\sim18\,\mathrm{Hz}$ at 1 second,
corresponding to the frequency stability of $9.5\times10^{-14}$. Our approach
provides an integrated and fully stabilized microcomb experiment scheme with no
requirement of $f-2f$ technique, which could be easily implemented and
generalized to various photonic platforms, thus paving the way towards the
portable and ultraprecise optical sources for high precision spectroscopy.
