# entropy_profile_from_CFT¶

tenpy.tools.fit.entropy_profile_from_CFT(size_A, L, central_charge, const)[source]

Expected profile for the entanglement entropy at a critical point.

Conformal field theory predicts the entanglement entropy for cutting a ground state of a finite, critical (i.e. gapless) system of length L into the left l and right L-l sites to be (eq. 2 of ):

$S(l, L) = \frac{c}{6} \log\left(\frac{2L}{\pi a} \sin\left(\frac{\pi l}{L}\right)\right) + \textrm{const}$

Here, c is the central charge of the system, and a is the lattice spacing, which we set to 1, and const is a non-universal constant.

Returns exactly that formula.