Integrated photonics source and detector of entangled photons

A method comprising:

• generating a pair of photons in a photon producing waveguide;
• coupling the pair of photons into a photonic vertical coupling waveguide, wherein the photon polarization modes of the pair of photons are coupled distinctly;
• converting one of the photons in the pair of photons so that both photons propagate in identical modes in different waveguides;
• providing the photons to one or more external devices;
• receiving the photons from the one or more external devices;
• and
• performing interferometry on the received photons.

A system comprising:

• a first waveguide layer comprising a photon producing waveguide configured to provide two photons propagating in two orthogonal modes of a single waveguide;
• a second waveguide layer comprising a photon conditioning waveguide network, wherein the second waveguide layer is formed on the first waveguide layer, the second waveguide layer having a different index of refraction from the first waveguide layer;
• and
• a photon vertical coupling waveguide, coupling the two photons into the photon conditioning waveguide network, wherein the photon conditioning waveguide network converts the two photons to propagate in two different waveguides in a same mode;
• wherein the photon conditioning waveguide network provides the two photons as an output to an external device;
• wherein the photon conditioning waveguide network receives the two photons from the external device and provides the two photons to an interferometer.