Robustness of negativity of the Wigner function to dissipation

Non-Gaussian quantum states described by negative valued Wigner functions are important both for fundamental tests of quantum physics and for the emerging quantum information technologies. In this paper, we analyze their vulnerability to dissipation. We find the maximal amount of losses at which the negativity disappears and the rate of decrease of the negativity volume around in the vicinity of its zero. We analyze also, how the squeezing affects robustness of the quantum state to losses and show that in some cases the squeezing can improve the robustnes.