中国物理B ›› 2008, Vol. 17 ›› Issue (7): 2466-2477.doi: 10.1088/1674-1056/17/7/021

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Radiation forces on a three-level atom in the high-order Bessel beams

王正岭1, 印建平2   

  1. (1)Department of Physics, Jiangsu University, Zhenjiang 212013, China;State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China; (2)State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China
  • 收稿日期:2007-09-03 修回日期:2008-03-02 出版日期:2008-07-09 发布日期:2008-07-09
  • 基金资助:
    Project supported by the National Natural Science Foundation of China ( Grant Nos 10434060 and 10674047), the Natural Science Foundation of the Jiangsu Higher Institutions of China (Grant No 06KJB510020), and the Natural Science Foundation of Jiangsu University of China (Grant No 07JDG027).

Radiation forces on a three-level atom in the high-order Bessel beams

Wang Zheng-Ling(王正岭)a) b)† and Yin Jian-Ping(印建平)b) ‡   

  1. a Department of Physics, Jiangsu University, Zhenjiang 212013, China; b State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China
  • Received:2007-09-03 Revised:2008-03-02 Online:2008-07-09 Published:2008-07-09
  • Supported by:
    Project supported by the National Natural Science Foundation of China ( Grant Nos 10434060 and 10674047), the Natural Science Foundation of the Jiangsu Higher Institutions of China (Grant No 06KJB510020), and the Natural Science Foundation of Jiangsu University of China (Grant No 07JDG027).

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摘要： The general expressions of the average dissipative and dipole forces acting on a $\Lambda $-configuration three-level atom in an arbitrary light field are derived by means of the optical Bloch equations based on the atomic density matrix elements, and the general properties of the average dissipative and dipole forces on a three-level atom in the linearly-polarized high-order Bessel beams (HBBs) are analysed. We find a resonant property (with two resonant peaks) of the dissipative force and a non-resonant property (with two pairs of non-resonant peaks) of the dipole force on the three-level atom, which are completely different from those on the two-level atom. Meanwhile we find a saturation effect of the average dissipative force in the HBB, which comes from the saturation of the upper-level population. Our study shows that the general expressions of the average dissipative and dipole forces on the three-level atom will be simplified to those of the two-level atom under the approximation of large detuning. Finally, we study the axial and azimuthal Doppler cooling of atoms in 1D optical molasses composed of two counter-propagating HBBs and discuss the azimuthal influence of the HBB on the Doppler cooling limit. We also find that the Doppler limit of atoms in the molasses HBB is slightly below the conventional Doppler limit of ${\hbar \Ga} /({2k_{\rm B}})$ due to the orbital angular momentum $l\hbar $ of the HBB.

关键词: radiation forces, optical Bloch equations, three-level atom, azimuthal Doppler cooling

Abstract: The general expressions of the average dissipative and dipole forces acting on a $\Lambda $-configuration three-level atom in an arbitrary light field are derived by means of the optical Bloch equations based on the atomic density matrix elements, and the general properties of the average dissipative and dipole forces on a three-level atom in the linearly-polarized high-order Bessel beams (HBBs) are analysed. We find a resonant property (with two resonant peaks) of the dissipative force and a non-resonant property (with two pairs of non-resonant peaks) of the dipole force on the three-level atom, which are completely different from those on the two-level atom. Meanwhile we find a saturation effect of the average dissipative force in the HBB, which comes from the saturation of the upper-level population. Our study shows that the general expressions of the average dissipative and dipole forces on the three-level atom will be simplified to those of the two-level atom under the approximation of large detuning. Finally, we study the axial and azimuthal Doppler cooling of atoms in 1D optical molasses composed of two counter-propagating HBBs and discuss the azimuthal influence of the HBB on the Doppler cooling limit. We also find that the Doppler limit of atoms in the molasses HBB is slightly below the conventional Doppler limit of ${\hbar \varGamma} /({2k_{\rm B}})$ due to the orbital angular momentum $l\hbar $ of the HBB.

Key words: radiation forces, optical Bloch equations, three-level atom, azimuthal Doppler cooling

中图分类号:  (Atom cooling methods)

  • 37.10.De
37.10.Vz (Mechanical effects of light on atoms, molecules, and ions)