Unravelling PT Symmetry: Applications in Metamaterials

Physicists are always riveted in predicting how a physical system behaves as a function of time. We begin this review article by understanding various formalisms to study the dynamics of the systems. The once-accepted belief that the Hamiltonian had to be Hermitian to ensure real eigenvalues got crashed down by parity-time (PT) symmetry where the Hamiltonian is no longer Hermitian. Thus, the idea of PT symmetry demonstrated that Hamiltonian's Hermicity is not necessary but sufficient to ensure the real eigenvalues. In this review article, we clearly describe the fundamental principle of PT symmetry, its significant attributes and its evolution in various fields of Physics, especially in Optics. In recent years, an artificial material called metamaterial has gained phenomenal momentum due to its unusual electromagnetic properties. These subwavelength-scale artificial electromagnetic materials can provide a variety of mediums for exploring non-Hermitian phenomena. Thus, the implementation of PT symmetry in metamaterial opened up an extended range of unusual phenomena in light-matter interaction. This paper addresses recent developments in PT metamaterials and highlights a few of its applications.

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