Enhanced von Neumann Entropy in Dense Two-Level Ensembles

We investigate the equilibrium properties of the von Neumann entropy in a dense, dipole–dipole coupled ensemble of two-level emitters confined in a fully symmetric Dicke subspace, which additionally interact through a common thermal bath. The static dipole–dipole interactions are assumed to be strong, though remaining smaller than the transition frequency. Consequently, the resulting thermal equilibrium entropy of the ensemble is characterized as a function of these coupling strengths. As a consequence, we have demonstrated that the von Neumann entropy enhances when stronger dipole–dipole couplings among the two-level emitters are being involved. Furthermore, the entropy can even be reduced for an opposite sign of the dipole–dipole coupling strength compared to the former case.