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Abstract

We propose a scheme in which broadband nanostructures allow for an enhanced two-photon nonlinearity that generates squeezed light from far-detuned quantum emitters via collective resonance fluorescence. To illustrate the proposal, we consider a pair of two-level emitters detuned by 400 line widths that are coupled by a plasmonic nanosphere. It is shown that the reduced fluctuations of the electromagnetic field arising from the interaction between the emitters provide a means to detect their entanglement. Due to the near-field enhancement in the proposed hybrid systems, these nonclassical effects can be encountered outside both the extremely close separations limiting the observation in free space and narrow frequency bands in high-Q cavities. Our approach permits overcoming the fundamental limitations to the generation of squeezed light from noninteracting single emitters and is more robust against phase decoherence induced by the environment.