We propose the concept of one-sided quantum interference based on non-Hermitian metasurfaces.By designing bianisotropic metasurfaces with a non-Hermitian exceptional point, we show that quantum interference can exist only on only one side but not another. This is the quantum inheritance of unidirectional zero reflection in classical optics.The one-side interference can be further manipulated with tailor-made metasurface. With two photons simultaneously entering the metasurface from different sides, the probability for only outputting one photon on the side with reflection can be modified to zero as a one-sided destructive quantum interference while the output on another side is free of interference. We design the required bianisotropic metasurface and numerically demonstrate the proposed effect. The non-Hermitian bianisotropic metasurfaces provide more degrees of freedom in tuning two-photon quantum interference, in parallel to the celebrated Hong-Ou-Mandel effect.
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