Chip that entangles four photons opens up possibility of inviolable quantum encryption

https://phys.org/news/2024-08-chip-entangles-photons-possibility-inviolable.html

"4-photon Greenberg-Horne-Zeilinger entangled state... combines quantum dot technology with glass (easily prototyped) photonic circuits... single stage fabrication produces 3D waveguides... circuit reconfigurability via thermal shifters permits fine-tuning of photons' optical phases, essential for desired overlap... each photon entangled with other 3, so unauthorized access alters quantum correlations... security can't be broken... scalable production...  secure, efficient quantum communication"