Momentum-Space Entanglement Entropy as a Universal Signature of Dynamical Quantum Phase Transitions

Abstract

We introduce a momentum-space entanglement entropy to quantify quantum correlations between distinct momentum modes following a quench. We prove analytically in the transverse-field Ising (TFI) model and the Su-Schrieffer-Heeger (SSH) chain that every critical momentum $k^{*}$ associated with a dynamical quantum phase transition (DQPT) saturates its entanglement entropy to the maximal value $\ln{d}$ ($d=2$ in TFI and SSH models), coinciding with the vanishing of the Loschmidt echo. This saturation of mode entanglement thus provides a universal, direct signature of DQPTs. Our work thus establishes a unified, entanglement-based perspective on dynamical quantum phase transitions.