Fundamental bound on Wigner negativity generation from environmental collisions

arXiv:2610.32315v1 Announce Type: new Abstract: Beyond quadratic potentials, classical evolution laws are typically thought to arise from quantum theory as an approximate description. Here we show that classical evolution laws can emerge exactly, provided the environment interacts with the system via collisions. We use this to derive an inequality that lower bounds the distribution of environmental momentum kicks by the absolute value of the Fourier transform of the potential. We show that violating this inequality is necessary and sufficient for a non-quadratic potential to generate negativity from the set of positive Wigner functions. A simple consequence of this is a lower bound on the heating rate for a quantum system to evolve effectively classically.