2011/11/30 by Y. F. Zhang, L. Sheng, R. Shen +2 · 1 citation
Physics and Astronomy · #cond-mat.mes-hall #cond-mat.stat-mech
paper · pdf · doi:10.1088/0953-8984/26/10/105502
published as J. Phys.: Condens. Matter 26 (2014) 105502 · 14 pages, 6 figures
arxiv created 2014/02/23 · arxiv updated 2014/02/25
We study the relationship between bipartite entanglement, subsystem particle number and topology in a half-filled free fermion system. It is proposed that the spin-projected particle numbers can distinguish the quantum spin Hall state from other states, and can be used to establish a new topological index for the system. Furthermore, we apply the new topological invariant to a disordered system and show that a topological phase transition occurs when the disorder strength is increased beyond a critical value. It is also shown that the subsystem particle number fluctuation displays behavior very similar to that of the entanglement entropy. This provides a lower-bound estimation for the entanglement entropy, which can be utilized to obtain an estimate of the entanglement entropy experimentally.