Experimental demonstration of nonlinear quantum metrology with optimal quantum state  

作　　者：Xinfang Nie Jiahao Huang Zhaokai Li Wenqiang Zheng Chaohong Lee Xinhua Peng Jiangfeng Du 

机构地区：[1]CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China [2]Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China [3]Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China [4]Laboratory of Quantum Engineering and Quantum Metrology, School of Physics and Astronomy, Sun Yat-sen University (Zhuhai Campus) [5]Center for Optics and Optoelectronics Research, College of Science, Zhejiang University of Technology [6]State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University (Guangzhou Campus) [7]Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University

出　　处：《Science Bulletin》2018年第8期469-476,共8页科学通报（英文版）

基　　金：supported by the National Key Basic Research Program of China(2013CB921800 and 2014CB848700);the National Science Fund for Distinguished Young Scholars of China(11425523);the National Natural Science Foundation of China(11374375,11574405,11375167,11605153 and 11704420);the Strategic Priority Research Program(B)of the CAS(XDB01030400);the Key Research Program of Frontier Sciences of the CAS(QYZDY-SSW-SLH004);partially supported by the National Postdoctoral Program for Innovative Talents of China(BX201600198)

摘　　要：Nonlinear quantum metrology may exhibit better precision scalings. For example, the uncertainty of an estimated phase may scale as △φ∝ 1/N2 under quadratic phase accumulation, which is 1/N times smal-ler than the linear counterpart, where N is probe number. Here, we experimentally demonstrate the non-linear quantum metrology by using a spin-I（I 〉 1/2） nuclear magnetic resonance （NMR） ensemble that can be mapped into a system ofN = 2I spin-1/2 particles and the quadratic interaction can be utilized for the quadratic phase accumulation. Our experimental results show that the phase uncertainty can scale as △φ∝1/（N2-1） by optimizing the input states, when N is an odd number. In addition, the interferomet-tic measurement with quadratic interaction provides a new way for estimating the quadrupolar coupling strength in an NMR system. Our system may be further extended to exotic nonlinear quantum metrology with higher order many-body interactions.Nonlinear quantum metrology may exhibit better precision scalings. For example, the uncertainty of an estimated phase may scale as ??∝1/(N^2) under quadratic phase accumulation, which is 1/N times smaller than the linear counterpart, where N is probe number. Here, we experimentally demonstrate the nonlinear quantum metrology by using a spin-I(I > 1/2) nuclear magnetic resonance(NMR) ensemble that can be mapped into a system of N=2I spin-1/2 particles and the quadratic interaction can be utilized for the quadratic phase accumulation. Our experimental results show that the phase uncertainty can scale as ??∝1/(N^2-1)by optimizing the input states, when N is an odd number. In addition, the interferometric measurement with quadratic interaction provides a new way for estimating the quadrupolar coupling strength in an NMR system. Our system may be further extended to exotic nonlinear quantum metrology with higher order many-body interactions.

关 键 词：Quantum information Quantum simulation Quantum metrology Quantum Fisher information Nuclear magnetic resonance Quadrupolar nuclei 

分 类 号：O413[理学—理论物理]