Shining a laser at a GaAs metasurface (i.e., not optical), the good old folks at Sandia National Laboratories and the Max Planck Institute for the Science of Light created a complex web of photon entanglements with all pairs entangled together. Some pairs are entangled at different wavelengths and emerge in the direction of the incoming laser beam. Hmmm…
https://www.spacedaily.com/reports/Through_the_quantum_looking_glass_999.html