Experimental Demonstration of Controllable PT and anti-PT Coupling in a non-Hermitian Metamaterial

The work studies non-Hermitian physics in an electromagnetic metamaterial, where gain/loss and dissipative coupling can produce either parity-time (PT) symmetry or its conjugate counterpart, anti-PT symmetry. The authors report an experimental demonstration that the coherence of complex dissipative coupling can control the transition between PT and anti-PT symmetry. They also state that achieving the anti-PT symmetric phase is independent of variations in dissipation. They further observe phase transitions when the system crosses exceptional points in both PT and anti-PT configurations. These transitions are controlled by manipulating the frequency and dissipation of resonators. Overall, the abstract frames the result as a design route for exploring non-Hermitian physics and enabling practical use of a controllable Hamiltonian in metamaterials.