  Atomic array coupled to a one-dimensional nanophotonic waveguide allows
photon-mediated dipole-dipole interactions and nonreciprocal decay channels,
which hosts many intriguing quantum phenomena owing to its distinctive and
emergent quantum correlations. In this atom-waveguide quantum system, we
theoretically investigate the atomic excitation dynamics and its transport
property, specifically at an interface of dissimilar atomic arrays with
different interparticle distances. We find that the atomic excitation dynamics
hugely depends on the interparticle distances of dissimilar arrays and the
directionality of nonreciprocal couplings. By tuning these parameters, a
dominant excitation reflection can be achieved at the interface of the arrays
in the single excitation case. We further study two effects on the transport
property-of external drive and of single excitation delocalization over
multiple atoms, where we manifest a rich interplay between multi-site
excitation and the relative phase in determining the transport properties.
Finally, we present an intriguing trapping effect of atomic excitation by
designing multiple zones of dissimilar arrays. Similar to the single
excitations, multiple excitations are reflected from the array interfaces and
trapped as well, although complete trapping of many excitations together is
relatively challenging at long time due to a faster combined decay rate. Our
results can provide insights to nonequilibrium quantum dynamics in dissimilar
arrays and shed light on confining and controlling quantum registers useful for
quantum information processing.
