  The emerging field of on-chip integration of nanophotonic devices and cold
atoms offers extremely-strong and pure light-matter interaction schemes, which
may have profound impact on quantum information science. In this context, a
long-standing obstacle is to achieve strong interaction between single atoms
and single photons, while at the same time trap atoms in vacuum at large
separation distances from dielectric surfaces. In this work, we study new
waveguide geometries that challenge these conflicting objectives. The designed
photonic crystal waveguide is expected to offer a good compromise, which
additionally allows for easy manipulation of atomic clouds around the
structure, while being tolerant to fabrication imperfections.
