Collective single excitation dynamics in a chirally coupled atomic chain

We theoretically study the collective single excitation dynamics 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 in 1D reservoirs, which allow infinite-range couplings between atoms. When a single photon interacts with part of the atomic chain from a side excitation, the long-time decay can be further prolonged 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 a unidirectional 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 collective excitation dynamics and the light-induced atom–atom correlations in such 1D nanophotonics platforms and offer rich opportunities in potential applications of quantum storage of photons. (paper)