Quantum metrology with unitary parametrization processes
arXiv:1409.4057 · doi:10.1038/srep08565
Abstract
Quantum Fisher information is a central quantity in quantum metrology. We discuss an alternative representation of quantum Fisher information for unitary parametrization processes. The highlight of this representation is that all information of parametrization transformation, i.e., the entire dynamical information, is totally involved in a Hermitian operator H. Utilizing this representation, quantum Fisher information is only determined by H and the initial state. We apply this representation in a collective spin system and show the specific expression of H. For a simple case, a spin-half system, the quantum Fisher information is given and the optimal states to access maximum quantum Fisher information are found. Furthermore, for an exponential form initial state, an analytical expression of quantum Fisher information by H operator is provided. The multiparameter quantum metrology is also considered and discussed utilizing this representation in the last.
6 pages, 2 figures
References in corpus (9)
- Beating the Standard Quantum Limit with Four Entangled Photons
- Quantum speed limit for physical processes
- Generalized Limits for Single-Parameter Quantum Estimation
- Optimal estimation of joint parameters in phase space
- Optimal Quantum-Enhanced Interferometry
- Collectively enhanced quantum measurements at the Heisenberg limit
- Multiple phase estimation for arbitrary pure states under white noise
- Quantum interferometry with binary-outcome measurements in the presence of phase diffusion
- Multiple phase estimation in quantum cloning machines