Hyungwon Kim

Ballistic spreading of entanglement in a diffusive nonintegrable system.

We study the time evolution of the entanglement entropy of a one-dimensional nonintegrable spin chain, starting from random nonentangled initial pure states. We use exact diagonalization of a nonintegrable quantum Ising chain with transverse and longitudinal fields to obtain the exact quantum dynamics. We show that the entanglement entropy increases linearly with time before finite-size saturation begins, demonstrating a ballistic spreading of the entanglement, while the energy transport in the same system is diffusive. Thus, we explicitly demonstrate that the spreading of entanglement is much faster than the energy diffusion in this nonintegrable system.

Entanglement spreading in a many-body localized system

Motivated by the findings of logarithmic spreading of entanglement in a many-body localized system, we identify and untangle two factors contributing to the spreading of entanglement in the fully many-body localized phase, where all many-body eigenstates are localized. Performing full diagonalizations of an

Thermalization of entanglement.

XXZ

Heat and spin transport in a cold atomic Fermi gas

spin model with random longitudinal fields, we demonstrate a linear dependence of the spreading rate on the decay length

Superdiffusive nonequilibrium motion of an impurity in a Fermi sea

(\ensuremath{\xi})

Testing whether all eigenstates obey the eigenstate thermalization hypothesis.

of the effective interaction between localized pseudospins (l-bits), which depends on the disorder strength, and on the final value of entanglement per spin

Slowest local operators in quantum spin chains

({s}_{\ensuremath{\infty}})

Eigenstate thermalization and representative states on subsystems

, which primarily depends on the initial state. The entanglement entropy thus grows with time as

Interfering directed paths and the sign phase transition

\ensuremath{\sim}\ensuremath{\xi}\ifmmode\times\else\texttimes\fi{}{s}_{\ensuremath{\infty}}logt

A real-time impurity solver for DMFT

, providing support for the phenomenology of many-body localized systems proposed by Huse and Oganesyan.