Enhancing nonclassical and entanglement properties of trio coherent states by photon-addition

Abstract

Trio coherent states as a kind of three-mode entangled state were introduced and studied. Some nonclassical characteristics of them such as higher-order antibunching, three-mode sum-squeezing and intermodal entanglement have been well revealed. In this paper, we further confirm their nonclassicality by examining negativity of Wigner function and non-Gaussian feature. However, our main purpose is to show that all the above-mentioned quantum properties of the trio coherent state can be enhanced by simultaneously adding photons to each mode of the state. In particular, we demonstrate that such so-called photon-added trio coherent states can possess three-mode sum-squeezing while the original trio coherent state (without photon-addition) cannot. In general, we show analytically and graphically how the degree of nonclassicality and/or entanglement depends on the number of added photons. Furthermore, we also consider a beamsplitter-based scheme for generation of the photon-added trio coherent states and evaluate the fidelity as well as the success probability as functions of the beamsplitter's parameter and the number of added photons.