Geometry-Enhanced Collective Emission and Spin Squeezing in Ordered Atomic Arrays 

Atom–light interactions underpin a wide range of many-body quantum phenomena. In free space, atoms radiate into a continuum of photonic modes, giving rise to long-range photon-mediated interactions and modified radiative behavior. Unlike cavity systems, genuinely collective decay and superradiance in free space are typically strongest only when interatomic separations are much smaller than the optical wavelength, which is challenging to achieve experimentally. In this talk, we show how tailoring the spatial arrangement and density of atomic ensembles can nevertheless enhance collective emission and realize superradiant dynamics in free space. Building on a driven–dissipative cavity protocol in which collective dissipation and strong symmetries generate an atom-number-dependent Berry phase and effective one-axis-twisting dynamics, we identify conditions under which an analogous dissipative one-axis-twisting mechanism can be realized in free space using only native dipolar interactions. This opens a path toward generating metrologically useful spin-squeezed states in optical lattice clocks and tweezer arrays, enabling new avenues for dissipative entanglement generation and quantum-enhanced metrology.