We consider two -symmetric models, consisting of two or three single-mode cavities. In both models, the cavities are coupled to each other by linear interactions, forming a linear chain. Additionally, the first and last of such cavities interact with an environment. Since the models are -symmetric, they are described by non-Hermitian Hamiltonians that, for a specific range of system parameters, possess real eigenvalues. We show that in the models considered in the article, the steering generation process strongly depends on the coupling strengths and rates of the gains/losses in energy. Moreover, we find the values of parameters describing the system for which the steering appears.
We consider a -symmetric system that involves three optical resonant elements coupled together. We investigate the quantum correlations between subsystems by calculating bipartite and tripartite entanglement. We show that when -symmetry is maintained, the correlations between subsystems strongly depend on the parameters describing the interaction between them and characterizing the gain and loss of energy in the system’s active and passive elements. We estimate the range of interaction parameter values for which the strongest bipartite and tripartite entanglement can be produced. Additionally, we show that the discussed system can be a source of stable entangled states.
We consider an Ising-type model of six interacting spins in a closed circular configuration. We discuss two scenarios in which the system is initially in either an entangled or a product state. In the first scenario, we analyze how entanglement is transferred among pairs of spins and how the coupling strength affects such a transfer. In the second scenario, we demonstrate that the creation of a strongly entangled state depends on the coupling parameters. We demonstrate that careful selection of the coupling strength can increase the degree of entanglement generated in the system, as measured by negativity, and control which spin pair becomes strongly entangled. Additionally, the relationship between linear entropy—a measure of mixedness—and negativity, a measure of entanglement, is discussed.