On Exponentially Long Prethermalization Timescales in Isolated Quantum Systems

We study prethermalization in time‐independent quantum many‐body systems on a ‐dimensional lattice with an extensive local Hamiltonian , in the regime where . We prove that the prethermal timescale is exponential in , where is an explicit scale determined by the locality exponent and the local norm of . We also construct two extensive local quasi‐conserved quantities whose variation remains exponentially small throughout this time interval.