2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/91296We give a simple proof of a formula for the minimal time required to simulate a two-qubit unitary operation using a fixed two-qubit Hamiltonian together with fast local unitaries. We also note that a related lower bound holds for arbitrary n-qubit gates.6 pagesQuantum Physicstext