The collective response of an atomic ensemble is shaped by its macroscopic environment. We demonstrate this effect in the near-resonant transmission of light through a thermal rubidium vapor confined in a planar nanocavity. Our model reveals density-dependent line shifts and broadenings beyond continuous electrodynamics models that oscillate with cavity width and have been observed in recent experiments. We predict that the amplitudes of these oscillations can be controlled by coatings that modify the cavity's Finesse.
We observe a density-dependent collective suppression of optical pumping between the hyperfine ground states in an array of submicrometer-sized clouds of cold rubidium atoms. The suppressed Raman transition rate can be explained by strong resonant dipole-dipole interactions that are enhanced by increasing atom density. The observations are consistent with stochastic electrodynamics simulations that incorporate the effects of the nonlinear population transfer via internal atomic levels embedded in a coupled-dipole model.
We show that two-time, second-order correlations of scattered photons from planar arrays and chains of atoms display nonclassical features that can be described by a superatom picture of the canonical single-atom $g_2(τ)$ resonance fluorescence result. For the superatom, the single-atom linewidth is replaced by the linewidth of the underlying collective low light-intensity eigenmode. Strong light-induced dipole-dipole interactions lead to a correlated response, suppressed joint photon detection events, and dipole blockade that inhibits multiple excitations of the collective atomic state. For t…
We experimentally study resonant light scattering by a one-dimensional randomly filled chain of cold two-level atoms. By a local measurement of the light scattered along the chain, we observe constructive interferences in light-induced dipole-dipole interactions between the atoms. They lead to a shift of the collective resonance despite the average interatomic distance being larger than the wavelength of the light. This result demonstrates that strong collective effects can be enhanced by structuring the geometrical arrangement of the ensemble. We also explore the high intensity regime where a…
We develop a theoretical formalism for the study of light-induced motion of atoms trapped in a two-dimensional (2D) array, considering the effect of multiple scattering of light between the atoms. We find that the atomic motion can be described by a collective diffusion equation, wherein laser-induced dipole-dipole forces couple the motion of different atoms. This coupling leads to the formation of collective mechanical modes of the array atoms, whose spatial structure and stability depend on the parameters of the illuminating laser and the geometry of the 2D array. We demonstrate the applicat…
We report coherent interactions within an ensemble of silicon-vacancy color centers in diamond. The interactions are ascribed to resonant dipole-dipole coupling. Further, we demonstrate control over resonant center pairs by using a driving optical pulse to induce collective, interaction-enabled Rabi-oscillations in the ensemble. Non-resonant center pairs do not undergo collective oscillations.
Fully inverted atoms placed at exactly the same location synchronize as they deexcite, and light is emitted in a burst (known as "Dicke's superradiance"). We investigate the role of finite interatomic separation on correlated decay in mesoscopic chains, and provide an understanding in terms of collective jump operators. We show that the superradiant burst survives at small distances, despite Hamiltonian dipole-dipole interactions. However, for larger separations, competition between different jump operators leads to dephasing, suppressing superradiance. Collective effects are still significant…
By utilizing strong optical resonant interactions in arrays of atoms with electric dipole transitions, we show how to synthesize collective optical responses that correspond to those formed by arrays of magnetic dipoles and other multipoles. Optically active magnetism with the strength comparable with that of electric dipole transitions is achieved in collective excitation eigenmodes of the array. By controlling the atomic level shifts, an array of spectrally overlapping, crossed electric and magnetic dipoles can be excited, providing a physical realization of a nearly-reflectionless quantum H…
We study the fluctuation-mediated interactions between two atoms in the presence of an aplanatic lens, demonstrating an enhancement in their resonant dipole-dipole interaction. We derive the field propagation of the linear optical system in terms of the electromagnetic Green's tensor for an aplanatic lens. The collective internal atomic dynamics is analyzed via a Lindblad master equation, which allows one to characterize the dispersive and dissipative interactions between atoms. We thus demonstrate that the resonant dipole-dipole coupling between the atoms can be enhanced in the focal plane of…
We investigate an attractive force caused by light induced dipole-dipole interactions in freely expanding ultracold 87Rb atoms. This collective, light-triggered effect results in a self-confining potential with interesting features: it exhibits nonlocal properties, is attractive for both red and blue-detuned light fields and induces a remarkably strong force that depends on the gradient of the atomic density. The experimental data are discussed in the framework of a theoretical model based on a local-field approach for the light scattered by the atomic cloud.
We study strong light-mediated resonant dipole-dipole interactions in two-dimensional planar lattices of cold atoms. We provide a detailed analysis for the description of the dipolar point emitter lattice plane as a "super-atom", whose response is similar to electromagnetically-induced transparency, but which exhibits an ultra-narrow collective size-dependent subradiant resonance linewidth. The super-atom model provides intuitively simple descriptions for the spectral response of the array, including the complete reflection, full transmission, narrow Fano resonances, and asymptotic expressions…
