Multipartite quantum nonlocality and topological quantum phase transitions in a spin-1/2 two-leg Kitaev ladder

Multipartite nonlocality, a measure of multipartite quantum correlations, is used to characterize topological quantum phase transitions (QPTs) in an infinite-size spin-1/2 two-leg Kitaev ladder model. First of all, the nonlocality measure 𝒮 is singular at the critical points, thus these topological QPTs are accompanied by dramatic changes of multipartite quantum correlations. The influence of the inter-chain coupling upon multipartite nonlocality is also investigated. Furthermore, we carry out scaling analysis and find that the logarithm measure scales linearly as log _2𝒮_n ∼𝒦 n +b , with n the length of the concerned subchain. It is clear that the slope 𝒦 plays a central role in the large- n behavior of the nonlocality in the ladder. Especially, as n increases, we find the finite-size slope 𝒦_n converges slowly in the _x,y phases which present non-local string orders, and quite rapidly in the _0 phase which does not present any string order. We figure out a clear picture to explain these different behaviors. Graphic abstract