Time-reversed Young's experiment: Deterministic, diffractionless second-order interference effect

Abstract: The classic Young's double-slit experiment exhibits first-order interference, producing alternating bright and dark fringes modulated by the diffraction effect of the slits. In contrast, here we demonstrate that its time-reversed configuration produces an ideal, deterministic second-order 'ghost' interference pattern devoid of diffraction and first-order effect, with the size dependent on the dimensions of the `effectively extended light source.' Furthermore, the new system enables a range of effects and phenomena not available in traditional double-slit interference studies, including the formation of programmed and digitized interference fringes and the coincidence of the pattern plane and the source plane. Despite the absence of first-order interference, our proposed experiment does not rely on nonclassical correlations or quantum entanglement. The elimination of diffraction through time-reversal symmetry holds promise for advancing superresolution optical imaging and sensing techniques beyond existing capabilities.