Resumen: It has been shown elsewhere that two spatially separated atoms can jointly absorb one photon, whose frequency is equal to the sum of the transition frequencies of the two atoms. We describe this process in the presence of an ensemble of many two-level atoms and show that it can be used to generate spin squeezing and entanglement. This resonant collective process allows us to create a sizable squeezing already at the single-photon limit. It represents a way to generate many-body spin-spin interactions, yielding a two-axis twisting-like interaction among the spins, which is very efficient for the generation of spin squeezing. We perform explicit calculations for ensembles of magnetic molecules coupled to a superconducting coplanar cavities. This system represents an attractive on-chip architecture for the realization of improved sensing. Idioma: Inglés DOI: 10.1103/PhysRevA.101.053818 Año: 2020 Publicado en: Physical Review A 101, 5 (2020), 053818 [13 pp] ISSN: 2469-9926 Factor impacto JCR: 3.14 (2020) Categ. JCR: PHYSICS, ATOMIC, MOLECULAR & CHEMICAL rank: 10 / 37 = 0.27 (2020) - Q2 - T1 Categ. JCR: OPTICS rank: 31 / 99 = 0.313 (2020) - Q2 - T1 Factor impacto SCIMAGO: 1.391 - Atomic and Molecular Physics, and Optics (Q1)