Quantum Fisher information and coherence of an atom in a dissipative cavity

In this work, we investigate quantum Fisher information (QFI) and quantum coherence (QC) of an atom in a dissipative cavity. In a zero-temperature reservoir and with one excitation number, we obtain the analytical solutions of QFI and QC as well as their relationship for Ohmic and Lorentzian reservoirs, respectively. The results show that both the atom-cavity coupling and the cavity-reservoir coupling can effectively protect QFI and QC. In particular, QFI and QC will tend to their stable values when the atom-cavity coupling or cavity-reservoir coupling is larger than a certain value. QC can augment QFI and can effectively improve the quantum metrology. In addition, we give a physical explanation of the dynamic behavior of QFI and QC using the decoherence rate.