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Modern high-definition display and augmented reality technologies require the development of ultracompact micro- and nano-pixels with colors covering the full gamut and high brightness. In this regard, lasing nano-pixels emitting light in the spectral range 400-700 nm are highly demanded. Despite progress in red, green, and ultraviolet nanolasers, the demonstrated blue-range (400-500 nm) single-particle-based lasers are still not subwavelength yet. Here we fabricate CsPbCl$_3$ cubic-shaped single-crystal nanolasers on a silver substrate by wet chemistry synthesis, producing their size range around 100-500 nm, where the nanoparticle with sizes 0.145$\mu$m$\times$0.195$\mu$m$\times$0.19$\mu$m and volume 0.005 $\mu$m$^3$ (i.e. $\sim\lambda^3$/13) is the smallest nanolaser among the lasers operating in the blue range reported so far, with emission wavelength around $\lambda\approx 415$ nm. Experimental results at a temperature of 80 K and theoretical modeling show that the CsPbCl$_3$ nanolaser is a polaritonic laser where exciton-polaritons are strongly coupled with Mie resonances enhanced by the metallic substrate. As a result, the combination of the strong excitonic response of CsPbCl$_3$ materials, its high crystalline quality, and optimized optical resonant properties resulting in a population-inversion-free lasing regime are the key factors making the proposed nanolaser design superior among previously reported ones in the blue spectral range.

Controlling the directionality of the acoustic scattering with single acoustic metaatoms has a key importance for reaching spatial routing of sound with acoustic metamaterials. In this paper, we present the experimental demonstration of the acoustic analogue of the Kerker effect realized in a two-dimensional coiled-space metaatom. By engineering the interference between monopolar and dipolar resonances within a high-index acoustic metaatom, we achieve directional scattering with suppressed backward or forward response at the first and second Kerker conditions respectively. Experimental measurements of the scattered pressure field, in a parallel-plate waveguide environment, show good agreement with the full-wave simulations. Our results validate the feasibility of Kerker-inspired wave control in acoustic systems and open new opportunities for directional sound manipulation.