Probing Causation Dynamics in Quantum Chains near Criticality

Distinguishing causation from correlation is crucial and requires careful consideration. In this study, we utilize a recent quantum extension of Liang information to investigate causation in quantum chains across their phase diagram. Our analysis encompasses two distinct scenarios: (i) the Aubry-André-Harper model, characterized by a spectrum-wide phase transition, and (ii) the Anisotropic Transverse Field Ising (ANNNI) model, which demonstrates a ground state transition. We discern a notable shift in causation behavior across the critical point with each case exhibiting distinct hallmarks, different from correlation measures. Especially, in the latter case, we observe maximum causation in the ordered phase just preceding the critical point.