Integrability and Computability in Simulating Quantum Systems

An impossibility theorem on approximately simulating quantum non-integrable Hamiltonian systems is presented here. This result shows that there is a tradeo between the unitary property and the energy expectation conservation law in time-descretization of quantum non-integrable systems, whose classical counterpart is Ge-Marsden's impossibility result about simulating classically non-integrable Hamiltonian systems using integration schemes preserving symplectic (Lie-Poisson) property.