Quantum Fisher information is a central quantity in quantum metrology. Wediscuss an alternative representation of quantum Fisher information for unitaryparametrization processes. The highlight of this representation is that allinformation of parametrization transformation, i.e., the entire dynamicalinformation, is totally involved in a Hermitian operator H. Utilizing thisrepresentation, quantum Fisher information is only determined by H and theinitial state. We apply this representation in a collective spin system andshow the specific expression of H. For a simple case, a spin-half system, thequantum Fisher information is given and the optimal states to access maximumquantum Fisher information are found. Furthermore, for an exponential forminitial state, an analytical expression of quantum Fisher information by Hoperator is provided. The multiparameter quantum metrology is also consideredand discussed utilizing this representation in the last.
展开▼
