[EN] We consider bipartite entangled states that cannot outperform separable states in any linear
interferometer. Then, we show that these states can still be more useful metrologically than separable
states if several copies of the state are provided or an ancilla is added to the quantum system. We present a
general method to find the local Hamiltonian for which a given quantum state performs the best compared
to separable states. We obtain analytically the optimal Hamiltonian for some quantum states with a high
symmetry. We show that all bipartite entangled pure states outperform separable states in metrology. Some
potential applications of the results are also suggested.