A Double Take on Unconventional Photon Blockade

Many quantum technologies require light sources that emit a precise number of photons. Examples include quantum cryptography, which uses individual photons for secure communication, and quantum imaging, which harnesses wave packets of a fixed number of photons to achieve enhanced resolution. A promising method for quickly generating single photons exploits an emitter-cavity system and the so-called photon-blockade effect. Here, the system acts as a photon filter for a laser, allowing the transit of only one photon at a time. Now two independent teams have overcome a major engineering challenge to realizing photon blockade in practical systems [1, 2]. These demonstrations take the effect one step closer to implementation in quantum technologies.