  We experimentally study the ergodic dynamics of a 1D array of 12
superconducting qubits with a transverse field, and identify the regimes of
strong and weak thermalization with different initial states. We observe
convergence of the local observable to its thermal expectation value in the
strong-thermalizaion regime. For weak thermalization, the dynamics of local
observable exhibits an oscillation around the thermal value, which can only be
attained by the time average. We also demonstrate that the entanglement entropy
and concurrence can characterize the regimes of strong and weak thermalization.
Our work provides an essential step towards a generic understanding of
thermalization in quantum systems.
