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arXiv · 1111.0791

Entanglement, subsystem particle numbers and topology in free fermion systems

Y. F. Zhang·L. Sheng·R. Shen·Rui Wang·D. Y. Xing
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Abstract

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.

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Y. F. Zhang, L. Sheng, R. Shen, Rui Wang, D. Y. Xing. 2014-02-23. Entanglement, subsystem particle numbers and topology in free fermion systems. https://doi.org/10.1088/0953-8984%2F26%2F10%2F105502

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