Anomalous Electromagnetic Tunneling with Bianisotropic Zero Index Media

We reveal an unexplored form of tunneling for electromagnetic waves which features opposite behaviors for the electric and magnetic fields, with one turning into a growing field, and the other a decaying field, in a medium that exhibits both ε-µ-zero and bianisotropy. Our work provides a new mechanism for manipulating electromagnetic waves for novel device applications.<br/>Quantum tunneling is one of the most fundamental phenomena in quantum mechanics, which underlies many important phenomena and applications that include photosynthesis, nuclear fusion, quantum computing, and scanning tunneling microscopy. Inside a barrier, the quantum wave loses its spatially oscillatory feature, and becomes a monotonically decaying wave. It generally leads to a transmission that drops exponentially with the height and the width of the barrier. Tunneling is not limited to quantum systems, but a universal phenomenon that governs all forms of waves, including electromagnetic waves, which is a vector wave that contains time-oscillating electric and magnetic fields.<br/>Here, by engineering the complex electromagnetic responses of metamaterials, we show that an incident electromagnetic wave can be manipulated to experience anomalous tunneling accompanied by a growing electric or magnetic field. This phenomenon is based on the combination of two unique electromagnetic properties enabled by metamaterials, ε-µ-zero (EMZ) that decouples the electric field and magnetic field, and bianisotropy that leads to exponential behaviors of the two fields with opposite trends (decay and growth), respectively. when two BEMZ slabs of the same thickness but opposite κ are joined together, depending on the order of their combination, one of the fields (either electric field or magnetic field) can be selectively enhanced at the interface while the other one would be at its minimum, with the matched impedance at the incidence. This observation greatly enriches our understanding of tunneling of waves in electromagnetic systems. Importantly, the concentration of either electric or magnetic field individually provides more freedom for the field manipulation. The proposed modal can be applied to higher dimensions, such as the cylindrical and spherical coordinates for 2D/3D field focusing.