  Emitter ensembles interact collectively with the radiation field. In the case
of a one-dimensional array of atoms near a nanofiber, this collective
light-matter interaction does not only lead to an increased photon coupling to
the guided modes within the fiber, but also to a drastic enhancement of the
chirality in the photon emission. We show that near-perfect chirality is
already achieved for moderately-sized ensembles, containing 10 to 15 atoms.
This is of importance for developing an efficient interface between atoms and
waveguide structures with unidirectional coupling, with applications in quantum
computing and communication such as the development of non-reciprocal photon
devices or quantum information transfer channels.
