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Overcoming the diffraction limit has been a long-lasting pursuit for researchers owing to the great potential it offers in going beyond the fundamental resolution restriction in imaging processes. In acoustics, meta-lenses have been a promising way to achieve sub-wavelength imaging, the practical application of which, however, has been limited by expensive material manufacturing, complex system setup, and material loss. Here, we propose a set of procedures equivalent to a virtual super-lens that selectively amplifies the evanescent wave components in the measured acoustic field spectrum, thereby enabling super-resolution imaging without any auxiliary setups or purposely designed super-lens. The proposed virtual super-lens is experimentally verified by considering the imaging of an irregularly shaped sample with sub-wavelength features. We further demonstrate the robustness of the high-quality imaging performance remains acceptable with some environment background noises. In the light of the simple experimental setup involved, our proposed method is flexible and can be readily applied to various practical imaging scenarios. [ABSTRACT FROM AUTHOR]

Phase modulation has scarcely been mentioned in diffusive physical systems because the diffusion process does not carry the momentum like waves. Recently, non-Hermitian physics provides a unique perspective for understanding diffusion and shows prospects in thermal phase regulation, exemplified by the discovery of anti-parity-time (APT) symmetry in diffusive systems. However, precise control of thermal phase remains elusive hitherto and can hardly be realized, due to the phase oscillations. Here we construct the PT-symmetric diffusive systems to achieve the complete suppression of thermal phase oscillation. The real coupling of diffusive fields is readily established through a strong convective background, and the decay-rate detuning is enabled by thermal metamaterial design. We observe the phase transition of PT symmetry breaking with the symmetry-determined amplitude and phase regulation of coupled temperature fields. Our work shows the existence of PT symmetry in dissipative energy exchanges and provides unique approaches for harnessing the mass transfer of particles, wave dynamics in strongly scattering systems, and thermal conduction.