  We demonstrate integrated photonic circuits for quantum devices using
sputtered polycrystalline aluminum nitride (AlN) on insulator. The on-chip AlN
waveguide directional couplers, which are one of the most important components
in quantum photonics, are fabricated and show the output power splitting ratios
from 50:50 to 99:1. The polarization beam splitters with an extinction ratio of
more than 10 dB are also realized from the AlN directional couplers. Using the
fabricated AlN waveguide beam splitters, we observe the Hong-Ou-Mandel
interference with a visibility of 91.7 +(-) 5.66 %.
