Exact real time dynamics with free fermions in disguise

Abstract: We consider quantum spin chains with a hidden free fermionic structure, distinct from the Jordan-Wigner transformation and its generalizations. We express selected local operators with the hidden fermions. This way we can exactly solve the real time dynamics in various physical scenarios, including the computation of selected dynamical two point functions, in continuous or discrete time. In the latter case we build a quantum circuit that can be implemented on a quantum computer. With this we extend the family of classically simulable quantum many-body processes.