Collective Two-Photon Blockade Scales to 1/N² Antibunching

Researchers have demonstrated an increase in photon blockade, a key effect for generating quantum states of light, as the number of light-emitting atoms increases. This result defies the typical expectation that adding more elements would diminish signal clarity. The team, led by Lijuan Dong of Sapienza University, found that antibunching, a measure of how well photons are separated, improves with the number of emitters following a 1/N² scaling. This collective enhancement occurs through a two-photon interaction, where atoms emit and absorb photons only in pairs, demonstrating that collective two-photon couplings are a powerful mechanism for realizing photon…