Parity-time-symmetric epsilon-near-zero metamaterials

We study epsilon-near-zero (ENZ) metamaterials with balanced loss and gain characterized by parity-time (PT ) symmetry. Through the example of a wave tunneling phenomenon, we show that the ENZ regime is particularly suited for PT -symmetry-based phenomena, since it enhances the effects of feasibly small levels of gain (and loss). Overall, the combination of the ENZ and PT -symmetry concepts may pave the way to novel, and otherwise unattainable, propagation effects and anomalous light-matter interactions.