2006/04/04 by J. P. Keating, Jonathan P. Keating, Francesco Mezzadri +3 · 3 citations
Computer Science · Physics and Astronomy · #Quantum Information and Cryptography #Quantum and electron transport phenomena #Quantum many-body systems #quant-ph
paper · pdf · doi:10.1103/physreva.74.012311
published as Phys. Rev. A 74, 012311 (2006) · 6 pages, 4 figures
arxiv created 2006/04/04 · openalex publication_date 2006/07/18 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Bipartite entanglement in the ground state of a chain of N quantum spins can be quantified either by computing pairwise concurrence or by dividing the chain into two complementary subsystems. In the latter case the smaller subsystem is usually a single spin or a block of adjacent spins and the entanglement differentiates between critical and noncritical regimes. Here we extend this approach by considering a more general setting: our smaller subsystem SA consists of a comb of L spins, spaced p sites apart. Our results are thus not restricted to a simple area law, but contain nonlocal information, parametrized by the spacing p. For the XX model we calculate the von Neumann entropy analytically when N\ensuremath→\ensuremath∞ and investigate its dependence on L and p. We find that an external magnetic field induces an unexpected length scale for entanglement in this case.