Logarithmic Entanglement Lightcone in Many-Body Localized Systems
  We theoretically study the response of a many-body localized system to a local quench from a quantum information perspective. We find that the local quench triggers entanglement growth throughout the whole system, giving rise to a logarithmic lightcone. This saturates the modified Lieb-Robinson bound for quantum information propagation in many-body localized systems previously conjectured based on the existence of local integrals of motion. In addition, near the localization-delocalization transition, we find that the final states after the local quench exhibit volume-law entanglement. We also show that the local quench induces a deterministic orthogonality catastrophe for highly excited eigenstates, where the typical wave-function overlap between the pre- and post-quench eigenstates decays {\it exponentially} with the system size. 
Dong-Ling Deng, Xiaopeng Li, J. H. Pixley, Yang-Le Wu, and S. Das   Sarma
cond-mat.dis-nn cond-mat.stat-mech cond-mat.str-el quant-ph