Detecting coherence with respect to general quantum measurements  

作　　者：Yu-Cheng CHEN Jiong CHENG Wen-Zhao ZHANG Cheng-Jie ZHANG 

机构地区：[1]School of Physical Science and Technology,Ningbo University,Ningbo 315211,China [2]State Key Laboratory of Precision Spectroscopy,School of Physics and Electronic Science,East China Normal University,Shanghai 200241,China

出　　处：《Science China(Information Sciences)》2023年第8期48-56,共9页中国科学（信息科学）（英文版）

基　　金：supported by National Natural Science Foundation of China(Grant Nos.11734015,11704205,12074206);Open Funding Program from State Key Laboratory of Precision Spectroscopy(East China Normal University);K.C.Wong Magna Fund in Ningbo University。

摘　　要：Quantum coherence is crucial in quantum resource theory.Previous studies have mainly focused on standard coherence based on a complete orthogonal reference.Standard coherence has recently been extended to general positive-operator-valued measure(POVM)-based coherence,including block coherence as a special case.Therefore,it is necessary to construct block and POVM-based coherence witnesses to detect them.In this study,we present witnesses for block and POVM-based coherence and obtain the necessary and sufficient conditions for constructing these witnesses.We also discuss possible realizations of some block and POVM-based coherence witnesses in experiments and present examples of measuring block coherence witnesses based on real experimental data.Furthermore,we present an application of block coherence witnesses in a quantum-parameter estimation task with a degenerate Hamiltonian and estimate the unknown parameter by measuring the block coherence witnesses when the input state is block coherent.Finally,we prove that the quantum Fisher information of any block-incoherent state equals zero,which coincides with the result obtained from measuring block coherence witnesses.

关 键 词：coherence witness general quantum measurements block coherence POVM-based coherence quantum coherence 

分 类 号：O413[理学—理论物理]