Multipartite Nonlocality of Finite and Infinite Transverse‐Field Ising Model

Abstract

The multipartite nonlocality of finite and infinite transverse‐field Ising model is investigated. For the finite chain, the exact diagonalization method is used to study the multipartite nonlocality at zero and finite temperatures. It is found that the logarithm of nonlocality S presents the linear relationship with the chain length of N at zero temperature. The multipartite nonlocality S shows a peak value near the phase transition point, which can be used to characterize the quantum phase transition of the Ising model. The inherent physical mechanics is that the nonlocality S captures the effect of low‐lying states with a small energy gap. The nonlocality S at the finite temperature is also observed to be scaled as log2 S ≈ aN + b at any fixed magnetic field B, where a and b are fitting parameters. For the infinite chain, the thermal tensor network algorithm is used to examine the multipartite nonlocality. The behaviors of nonlocality S of the infinite chain at the finite temperature are similar to those of finite chain. Compared with the finite chain, the positions of the peak values of the multipartite nonlocality shift to the larger magnetic field, and the peak values are smaller than those of finite chain.