The stationarity test: a framework for learning quantum many-body systems from their thermal states
The stationarity test is a new method to learn quantum Hamiltonians from samples of thermal states or metastable states. It works by checking if a candidate Hamiltonian makes the state 'stationary' under specific dynamics, allowing for robust learning of both the system's structure (interactions) and its parameters (coefficients). This framework also proves an area law for metastable states.