中国物理B ›› 2021, Vol. 30 ›› Issue (3): 33201-.doi: 10.1088/1674-1056/abd772

所属专题： SPECIAL TOPIC — Quantum computation and quantum simulation

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  • 收稿日期:2020-10-15 修回日期:2020-11-13 接受日期:2020-12-30 出版日期:2021-02-22 发布日期:2021-02-22

Scheme to measure the expectation value of a physical quantity in weak coupling regime

Jie Zhang(张杰)1,2, Chun-Wang Wu(吴春旺)1,2, Yi Xie(谢艺)1,2, Wei Wu(吴伟)1,2, and Ping-Xing Chen(陈平形)1,2,†   

  1. 1 Department of Physics, College of Liberal Arts and Sciences, National University of Defense Technology, Changsha 410073, China; 2 Interdisciplinary Center for Quantum Information, National University of Defense Technology, Changsha 410073, China
  • Received:2020-10-15 Revised:2020-11-13 Accepted:2020-12-30 Online:2021-02-22 Published:2021-02-22
  • Contact: †Corresponding author. E-mail: pxchen@nudt.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 12004430 and 61632021) and the National Basic Research Program of China (Grant No. 2016YFA0301903).

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Abstract: In quantum mechanics, the expectation value of an operator can be measured by using the projective measurement, if the coupling between the measured system and pointer is strong enough. However in the weak coupling regime, the pointer can not show all the eigenvalue of the physical quantity directly due to the overlapping among the pointer states, which makes the measurement of the expectation value difficult. In this paper, we propose an expectation value measurement method in the weak coupling regime inspired by the weak measurement scheme. Compared to the projective measurement, our scheme has two obvious advantages. Experimentally we use the internal state and motional state of a single trapped 40Ca+ to establish the measurement scheme and realize the proof of principle demonstration of the scheme.

Key words: weak measurement, expectation value, trapped ions

中图分类号:  (Coherent control of atomic interactions with photons)

  • 32.80.Qk
03.65.Wj (State reconstruction, quantum tomography) 03.75.Be (Atom and neutron optics)