Metasurfaces based on resonant nanophotonic structures have enabled innovative types of flat-optics devices that often outperform the capabilities of bulk components, yet these advances remain largely unexplored for quantum applications. We show that nonclassical multiphoton interferences can be achieved at the subwavelength scale in all-dielectric metasurfaces. We simultaneously image multiple projections of quantum states with a single metasurface, enabling a robust reconstruction of amplitude, phase, coherence, and entanglement of multiphoton polarization-encoded states. One- and two-photon states are reconstructed through nonlocal photon correlation measurements with polarization-insensitive click detectors positioned after the metasurface, and the scalability to higher photon numbers is established theoretically. Our work illustrates the feasibility of ultrathin quantum metadevices for the manipulation and measurement of multiphoton quantum states, with applications in free-space quantum imaging and communications.

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We report on the realization of adiabatic light transfer in lithium niobate (LiNbO₃) waveguides. This peculiar adiabatic tunneling scheme was implemented in a three-waveguide coupling configuration with the intermediate waveguide being inclined with respect to the outer waveguides to facilitate the adiabatic passage process. We have investigated and determined the adiabatic conditions of the LiNbO₃ device in terms of the structure configuration of the waveguide system and found optimal structure parameters by both simulation and experimental approaches. Broadband adiabatic couplings of bandwidth ~456 and 185 nm and peak coupling efficiencies of >0.96 have been obtained with a 2-cm long device for TE- and TM-polarized fundamental modes, respectively. Longer (5 cm) devices were also studied and found to be useful in increasing the adiabaticity of the device, especially for the TM-polarized mode.

A high performance rotational EIT (REIT) system capable of producing better quality EIT images is developed by expanding the independent measurements. In this system, electrodes are attached to a rotational phantom tank which is driven by a microstepping motor. The measurement site of the electrode pairs can be precisely changed. We increase the independent measurements by moving electrodes from the original location to a subsequent location. Increasing the number of independent measurements enhances the resolution of the impedance image and improves the quality arising from the ill-posed condition. The experimental results clearly show the improvement of the REIT image. It is believed that this improvement will provide help in the field of electrical impedance tomography.