Connecting the von Neumann and Renyi entropies for Fermions
  We explore the relation between the von Neumann entropy and the Renyi entropies of integer orders for shift-invariant quasi-free Fermionic lattice systems. We investigate approximating the von Neumann entropy by a combination of integer-order Renyi entropies and give an estimate for the quality of such an approximation. 
Mark Fannes, Nicholas Van Ryn
quant-ph