Journal of Systems Engineering and Electronics ›› 2020, Vol. 31 ›› Issue (5): 908-915.doi: 10.23919/JSEE.2020.000069

• Electronics Technology • Previous Articles     Next Articles

Renormalization: single-photon processes of two-level system in free space

Chong WANG1,2,*(), Yong ZHU1,2(), Liangsheng LI1,2(), Hongcheng YIN1,2()   

  1. 1 Beijing Institute of Environment Features, Beijing 100854, China
    2 Science and Technology on Electromagnetic Scattering Laboratory, Beijing Institute of Environmental Features, Beijing 100854, China
  • Received:2019-07-04 Online:2020-10-30 Published:2020-10-30
  • Contact: Chong WANG E-mail:w.c_physics_2005@163.com;13810065549@qq.com;liliangshengbititp@163.com;yinhc207@126.com
  • About author:WANG Chong was born in 1987. He received his B.S. degree in 2010 and Ph.D. degree in 2016 from Peking University, Beijing, China, all in physics. He is now a senior engineer of the Science and Technology on Electromagnetic Scattering Laboratory, Beijing Institute of Environmental Features. His current research interests include electromagnetic fields, quantum radar and quantum field theory. E-mail: w.c_physics_2005@163.com|ZHU Yong was born in 1976. He received his B.S. degree from Harbin Institute of Technology, Harbin, China, in 1998, and his M.S. degree in electromagnetic field and microwave technique from the Second Academy of the Aerospace Industry Ministry, Beijing, China, in 2001. He is currently a senior researcher at the Science and Technology on Electromagnetic Scattering Laboratory, Beijing Institute of Environmental Features. His current research interests include numerical methods in electromagnetic fields, electromagnetic scattering and inverse scattering. E-mail: 13810065549@qq.com|LI Liangsheng was born in 1981. He received his B.S. in 2003 and M.S. degrees in 2006 from Beijing Institute of Technology, and his Ph.D. degree in 2009 from Institute of Theoretical Physical, Chinese Academy of Sciences, Beijing, China, all in physics. He is now a senior researcher of the Science and Technology on Electromagnetic Scattering Laboratory. His research interests include terahertz wave, metamaterial, quantum radar and phase transition. E-mail: liliangshengbititp@163.com|YIN Hongcheng was born in 1967. He received his B.S. degree from Northwest Telecommunication Engineering Institute, Xi'an, China, in 1986, his M.S. degree from the Second Academy of the Aerospace Industry Ministry, Beijing, China, in 1989, and his Ph.D. degree from Southeast University, Nanjing, China, in 1993, all in electromagnetic field and microwave technique. He is currently a senior researcher at the Science and Technology on Electromagnetic Scattering Laboratory, Beijing Institute of Environmental Features. His current research interests include numerical methods in electromagnetic fields, electromagnetic scattering and inverse scattering, radar target recognition. Dr. Yin is a fellow of Chinese Institute of Electronics. E-mail: yinhc207@126.com
  • Supported by:
    the National Natural Science Foundation of China(6149690025);This work was supported by the National Natural Science Foundation of China (6149690025)

Abstract:

The investigation on quantum radar requires accurate computation of the state vectors of the single-photon processes of the two-level system in free space. However, the traditional Weisskopf-Wigner (W-W) theory fails to deal with those processes other than spontaneous emission. To solve this problem, we provide a new method based on the renormalization theory. We evaluate the renormalized time-ordered Green functions associated with the single-photon processes, and relate them to the corresponding state vectors. It is found that the ultraviolet divergences generated by the Lamb shift and higher-order interactions can be systematically subtracted in the state vectors. The discussions on spontaneous emission and single-photon absorption are then presented to illustrate the proposed method. For spontaneous emission, we obtain the same results of the W-W theory. For single-photon absorption where W-W theory fails, we find that the two-level electric dipole first gets excited rapidly and then decays exponentially, and that the efficiency of the single-photon absorption declines as the bandwidth of the incident photon becomes narrow. The proposed method can improve the investigation on quantum radar.

Key words: single-photon process, two-level system (2LS), renormalization time-ordered Green function (RTGF), quantum radar