Abstract:
The quantum multiparameter estimation is very different from the classical multiparameter estimation due to Heisenberg’s uncertainty principle in quantum mechanics. When the optimal measurements for different parameters are incompatible, they cannot be jointly performed. We find a correspondence relationship between the inaccuracy of a measurement for estimating the unknown parameter with the measurement error in the context of measurement uncertainty relations. Taking this correspondence relationship as a bridge, we incorporate Heisenberg’s uncertainty principle into quantum multiparameter estimation by giving a trade-off relation between the measurement inaccuracies for estimating different parameters. For pure quantum states, this trade-off relation is tight, so it can reveal the true quantum limits on individual estimation errors in such cases. We apply our approach to derive the trade-off between attainable errors of estimating the real and imaginary parts of a complex signal encoded in coherent states and obtain the joint measurements attaining the trade-off relation. We also show that our approach can be readily used to derive the trade-off between the errors of jointly estimating the phase shift and phase diffusion without explicitly parametrizing quantum measurements.
Biography:
Xiaoguang Wang is a Professor at Zhejiang Sci-Tech University. He obtained his Ph.D. in physics from Changchun Institute of Physics, Chinese Academy of Sciences in 1998. His research interests include quantum information and computation theory, quantum optics, and condensed matter theory. More than 260 papers have been published and the papers were cited by SCI more than 8500 times. He obtained the special allowance of the State Council in 2006 and won the National Science Funds for Distinguished Young Scholars in 2010.
Seminar by the NYU-ECNU Institute of Physics at NYU Shanghai