We show both theoretically and experimentally that a pair of inductively coupled active LRC circuits (dimer), one with amplification and another with an equivalent amount of attenuation, display all the features which characterize a wide class of non-Hermitian systems which commute with the joint parity-time PT operator: typical normal modes, temporal evolution, and scattering processes. Utilizing a Liouvilian formulation, we can define an underlying PT -symmetric Hamiltonian, which provides important insight for understanding the behavior of the system. When the PT -dimer is coupled to transmission lines, the resulting scattering signal reveals novel features which reflect the PT -symmetry of the scattering target. Specifically we show that the device can show two different behaviors simultaneously, an amplifier or an absorber, depending on the direction and phase relation of the interrogating waves. Having an exact theory, and due to its relative experimental simplicity, PT -symmetric electronics offers new insights into the properties of PT -symmetric systems which are at the forefront of the research in mathematical physics and related fields.

We investigate magnetic nanostructures with balanced gain and loss and show that such configurations can result in a new type of dynamics for magnetization. Using the simplest possible set-up consisting of two coupled ferromagnetic films, one with loss and another one with a balanced amount of gain, we demonstrate the existence of an exceptional point where both the eigenfrequencies and eigenvectors become degenerate. This point corresponds to a particular value of gain and loss parameter α = αc. For α < αc the frequency spectrum is real, indicating stable dynamics, while for α > αc it is complex, signaling unstable dynamics which is, however, stabilized by nonlinearity.

We introduce a new family of generalized PT-symmetric cavities that involve gyrotropic elements and support reconfigurable unidirectional lasing modes. We derive conditions for which these modes exist and investigate a simple electronic circuit that experimentally demonstrates their feasibility in the radio-frequency domain.