  Fisher Information is a key notion in the whole field of quantum metrology.
It allows for a direct quantification of maximal achievable precision of
estimation of parameters encoded in quantum states using the most general
quantum measurement. It fails, however, to quantify the robustness of quantum
estimation schemes against measurement imperfections, which are always present
in any practical implementations. Here, we introduce a new concept of Fisher
Information Measurement Noise Susceptibility that quantifies the potential loss
of Fisher Information due to small measurement disturbance. We derive an
explicit formula for the quantity, and demonstrate its usefulness in analysis
of paradigmatic quantum estimation schemes, including interferometry and
super-resolution optical imaging.
