Computation of entanglement entropy in inhomogeneous free fermions chains by algebraic Bethe ansatz

The q-Racah polynomials from scalar products of Bethe states

“…This will be considered in a forthcoming paper. (iii) Furthermore, the results in this paper may also find applications in the study of the entanglement entropy and other correlations of inhomogeneous free fermionic models, since the associated reduced correlation matrix commutes with the Heun-Askey-Wilson operator, see [CNV19,BerCCV22b].…”

Absence of logarithmic enhancement in the entanglement scaling of free fermions on folded cubes

“…In the following, we investigate the scaling of S(j) as a function of j. The entanglement properties of inhomogeneous free-fermion chains solved by orthogonal polynomials have been intensely studied recently [30][31][32][33][34][35]. We fix the ratios κ := K/d and ξ := (d − L)/(j + 1) and use (53) to compute S(j) via exact numerical diagonalization of the chopped correlation matrix (51).…”