Entanglement spectrum and entropy scaling in a Kitaev chain with variable-range interaction


The entanglement spectrum was calculated for a contiguous block of spins in a Kitaev chain with a power law decay of interactions. Changes in the degeneracies of the four largest eigenvalues of the spectrum identify the quantum critical line separating the paramagnetic and anti-ferromagnetic phases of the model. Effective central charges along the critical lines are calculated by analyzing the finite-size scaling of the entanglement entropy with block length. For power law exponents that correspond to short-ranged interactions the effective central charge is that of free-fermionic models. For longer ranged interactions the obtained central charge deviates from this value.