Crossover from Poisson to Wigner-Dyson level statistics in spin chains with integrability breaking
Crossover from Poisson to Wigner-Dyson level statistics in spin chains with integrability breaking
We study numerically the evolution of energy-level statistics as an integrability-breaking term is added to the XXZ Hamiltonian. For finite-length chains, physical properties exhibit a cross-over from behavior resulting from the Poisson level statistics characteristic of integrable models to behavior corresponding to the Wigner-Dyson statistics characteristic of the random-matrix theory …