  We show that in 1+1 dimensional conformal field theories, exciting a state
with a local operator increases the Renyi entanglement entropies by a constant
which is the same for every member of the conformal family. Hence, it is an
intrinsic parameter that characterises local operators from the perspective of
quantum entanglement. In rational conformal field theories this constant
corresponds to the logarithm of the quantum dimension of the primary operator.
We provide several detailed examples for the second Renyi entropies and a
general derivation.
