Direct measurement of nonlocal quantum states without approximation  

作　　者：杨冈 杨然 龚彦晓 祝世宁 Gang Yang;Ran Yang;Yan-Xiao Gong;Shi-Ning Zhu(National Laboratory of Solid State Microstructure,School of Physics and Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210093,China)

机构地区：[1]National Laboratory of Solid State Microstructure,School of Physics and Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210093,China

出　　处：《Chinese Physics B》2023年第11期252-256,共5页中国物理B（英文版）

基　　金：Project supported by National Key Research and Development Program of China (Grant No. 2019YFA0705000);the National Natural Science Foundation of China (Grant No. 11974178)。

摘　　要：Efficient acquiring information from a quantum state is important for research in fundamental quantum physics and quantum information applications. Instead of using standard quantum state tomography method with reconstruction algorithm, weak values were proposed to directly measure density matrix elements of quantum state. Recently, similar to the concept of weak value, modular values were introduced to extend the direct measurement scheme to nonlocal quantum wavefunction. However, this method still involves approximations, which leads to inherent low precision. Here, we propose a new scheme which enables direct measurement for ideal value of the nonlocal density matrix element without taking approximations. Our scheme allows more accurate characterization of nonlocal quantum states, and therefore has greater advantages in practical measurement scenarios.

关 键 词：direct measurement quantum tomography nonlocal quantum state 

分 类 号：O413[理学—理论物理]