Von Neumann entropy and bipartite number fluctuation in quantum phase transitions

摘要

In order to characterize quantum phase transitions, we consider von Neumann entanglement entropy of bipartition systems. We propose a bipartition such as even-odd in a one-dimensional system or checkerboard in a two-dimensional case. The entanglement entropy successfully indicates the critical point in the spinless fermion system where the metal-insulator transition is known to exist. Furthermore, we calculate the bipartite number fluctuation which shows a shoulder near the transition.