  We theoretically study the quantum-coherence-enhanced subradiance in a
chiral-coupled atomic chain with nonreciprocal decay channels. The collective
radiation in this one-dimensional (1D) nanophotonics system results from the
resonant dipole-dipole interactions (RDDI) in 1D reservoirs, which allow
infinite-range couplings between atoms. When single photon interacts with part
of the atomic chain from a side excitation, the subradiant decay can be further
reduced when highly correlated states are initially excited. The excitation
plateau in the decay process can emerge due to the ordered population
exchanges, which presents one distinctive signature of long-range and
light-induced atom-atom correlations. Multiple time scales of the decay
behaviors also show up due to multiple scattering of light transmissions and
reflections in the chain. We further investigate the effect of atomic position
fluctuations, and find that the cascaded scheme with uni-directional coupling
is more resilient to the fluctuations, while the overall decay constant can be
increased due to large deviations. Our results present a fundamental study on
the subradiance and light-induced atom-atom correlations in such 1D
nanophotonics platforms, and offer rich opportunities in potential applications
of quantum storage of photons.
