Quantum networks are composed of quantum nodes that interact coherently through quantum channels, and open a broad frontier of scientific opportunities. An exciting frontier in this endeavor is the integration of otherwise `simple' quantum elements into complex quantum networks. In this context, there is active research to achieve lithographic quantum optical circuits, for which atoms are trapped near nanoscopic dielectric structures and 'wired' together by photons propagating through circuit elements. In this talk, I will discuss our results on trapping and interfacing ultracold atoms with optical nanofibers, and a recent experimental demonstration of collective band-edge nonlinearity with localized atoms in 1D photonic crystal waveguides. By trapping single atoms within vacuum spaces of a photonic crystal, new opportunities emerge for novel quantum transport phenomena, tunable long-range atomic interactions, and control of quantum vacuum forces. With strongly-coupled atom and photons near dispersive bandgaps, we can utilize genuine quantum dynamics at the level of single quanta to manipulate and examine entangled phases of light and matter, and to build a foundation for designing new quantum optical materials at ultracold temperature.