“…Their non-classicality was marked by the negativity of both Wigner and P functions surviving to some extent under damping as well. On the contrary, an M-photon-subtracted Gaussian state can be either classical or non-classical, depending on the input state ρG [24,25,26]. For instance, subtraction of photons from a coherent or a thermal state provides a classical non-Gaussian output [24,27].…”