Higher nonclassical properties and entanglement of photon-added two-mode squeezed coherent states

We investigate how photon addition operations affect some higher-order nonclassical properties and the intermodal entanglement of a non-Gaussian entangled state generated by adding photons to both modes of a two-mode squeezed coherent state (TMSCS). We show that the photon addition operation can enhance the degrees of the sum squeezing and the difference squeezing for appropriate combinations of several parameters involved in the TMSCS. We consider the existing Hillery-Zubairy entanglement criterion, and find that the quantity of Hillery-Zubairy E gets more negative not only for a larger value of the squeezing parameter r but also for greater values of photon addition numbers (m, n). Our results may imply that the highest enhancement is obtained when same number of operations (i.e., m=n) is applied to both modes. However, for the photon-added TMSCS (PA-TMSCS), the more violation to the Hillery-Zubairy inequality does not necessarily following strong sum squeezing and difference squeezing. This because their behaviors with three phases and squeezing parameter r involved in the TMSCS are somewhat different.