Quantum parameter estimation with general dynamics

Abstract

New tools for quantum parameter estimation: more general and more efficient Measuring the parameters of interest with high precision is essential for science and technology, where the main quest is to find the ultimate precision limit and the optimal schemes to attain it. For a general noisy dynamics, the identification of the ultimate precision limit usually requires certain assumptions. In this work, Haidong Yuan from the Chinese University of Hong Kong and Chi-Hang Fred Fung from Munich Research Center, Huawei Technologies provided a systematic method to obtain the ultimate precision limit for general dynamics which does not make any assumptions and is more efficient than existing methods. Their method is based on an extension of a popular tool, the Bures angle, from quantum states to quantum channels, which is expected to have wide applications not only in quantum metrology but in many other fields of quantum information science.