Characterizing entanglement robustness of N-qubit W superposition state against particle loss from quantum Fisher information

Abstract

We investigate the entanglement robustness of N-qubit W superposition state against particle loss with quantum Fisher information. In the noninteracting environment, the quantum Fisher information of reduced W superposition state is found same as the W superposition state when the number of qubits larger than 5, which shows very strong entanglement robustness compared to Twin-Fock state and Greenberger-Horne-Zeilinger state. Meanwhile, the effect of re-particle-loss is also studied and it presents a rapid decay of quantum Fisher information with the increase of losing qubits, indicating the weak entanglement robustness. In the interacting environment, the results show that the reduced W superposition state performs better than it in noninteracting environment. Alternatively, with the increase of qubits (N > 5) the reduced W superposition state behaves much more robust than original state. To vividly approach the real noisy environment, the effects of different decoherence channels are also considered.