Long-time rigidity to flux-induced symmetry breaking in quantum quench dynamics

We investigate how the breaking of charge conjugation symmetry C impacts on the dynamics of a half-filled fermionic lattice system after global quenches. We show that, when the initial state is insulating and the C symmetry is broken nonlocally by a constant magnetic flux, local observables, and correlations behave as if the symmetry were unbroken for a time interval proportional to the system size L. In particular, the local particle density of a quenched dimerized insulator remains pinned to 1/2 in each lattice site for an extensively long time, while it starts to significantly fluctuate only afterwards. Due to its qualitative resemblance to the sudden arrival of rapidly rising ocean waves, we dub this phenomenon the “tsunami effect.” Notably, it occurs even though the chiral symmetry is dynamically broken right after the quench. Furthermore, we identify a way to quantify the amount of symmetry breaking in the quantum state, showing that in insulators perturbed by a flux, it is exponentially suppressed as a function of the system size, while it is only algebraically suppressed in metals and in insulators with locally broken C symmetry. The robustness of the tsunami effect to weak disorder and interactions is demonstrated, and possible experimental realizations are proposed