Nonergodicity of entanglement and its complementary behavior to magnetization in an infinite spin chain
Aditi Sen, Ujjwal Sen, Maciej Lewenstein · Physical Review A · 2004
We consider the problem of the validity of a statistical mechanical description of two-site entanglement in an infinite spin chain described by the $XY$ model Hamiltonian. We show that the two-site entanglement of the state, evolved from the initial equilibrium state, after a change of the magnetic field, does not approach its equilibrium value. This suggests that two-site entanglement, like (single-site) magnetization, is a nonergodic quantity in this model. Moreover, we show that these two nonergodic quantities behave in a complementary way.