Nanoscale lattices create a broadband quantum light source

Researchers at the Universidad Autónoma de Madrid and the Instituto de Química Física Blas Cabrera have demonstrated a way to manipulate light at the quantum level using nanoscale lattices of quantum emitters. The work reveals that these lattices, functioning as quantum metasurfaces with subwavelength periods, can populate excitonic Bloch states with wavevectors exceeding the limits of conventional optics. In strong-driving regimes, the lattices produce a broadband background of photons, closely related to resonance fluorescence, and enter a bistable regime, a behavior contrasting sharply with classical systems, allowing for selective control of optical quantum nonlinearities. This bistable behavior enables the selective activation and deactivation of the optical quantum nonlinearities of the system. Subwavelength lattice periods enable the population of excitonic Bloch states with wavevectors that exceed the light cone’s limitations, a phenomenon not typically observed in conventional optics. This unusual behavior arises when a resonant plane wave interacts with the lattice, effectively altering the pathways available to excitons, quasiparticles representing excited states in the material.…