Entanglement capabilities of non-local Hamiltonians
  We quantify the capability of creating entanglement for a general physical interaction acting on two qubits. We give a procedure for optimizing the generation of entanglement. We also show that a Hamiltonian can create more entanglement if one uses auxiliary systems. 
W. D\"ur, G. Vidal, J. I. Cirac, N. Linden and S. Popescu