  The integration of quantum emitters with integrated photonics enables complex
quantum photonic circuits that are necessary for photonic implementation of
quantum simulators, computers, and networks. Thin-film lithium niobate is an
ideal material substrate for quantum photonics because it can tightly confine
light in small waveguides and has a strong electro-optic effect that can switch
and modulate single photons at low power and high speed. However, lithium
niobite lacks efficient single-photon emitters, which are essential for
scalable quantum photonic circuits. We demonstrate deterministic coupling of
single-photon emitters with a lithium niobate photonic chip. The emitters are
composed of InAs quantum dots embedded in an InP nanobeam, which we transfer to
a lithium niobate waveguide with nanoscale accuracy using a pick-and place
approach. An adiabatic taper transfers single photons emitted into the nanobeam
to the lithium niobate waveguide with high efficiency. We verify the single
photon nature of the emission using photon correlation measurements performed
with an on-chip beamsplitter. Our results demonstrate an important step toward
fast, reconfigurable quantum photonic circuits for quantum information
processing.
