中国物理B ›› 2015, Vol. 24 ›› Issue (6): 60702-060702.doi: 10.1088/1674-1056/24/6/060702

• GENERAL • 上一篇    下一篇

In-situ measurement of magnetic field gradient in a magnetic shield by a spin-exchange relaxation-free magnetometer

房建成a, 王涛a, 张红b, 李阳a, 蔡洪炜a   

  1. a School of Instrument Science and Opto-Electronics Engineering, Science and Technology on Inertial Laboratory, Beihang University, Beijing 100191, China;
    b School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China
  • 收稿日期:2014-11-03 修回日期:2014-12-24 出版日期:2015-06-05 发布日期:2015-06-05
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 61227902, 61374210, and 61121003).

In-situ measurement of magnetic field gradient in a magnetic shield by a spin-exchange relaxation-free magnetometer

Fang Jian-Cheng (房建成)a, Wang Tao (王涛)a, Zhang Hong (张红)b, Li Yang (李阳)a, Cai Hong-Wei (蔡洪炜)a   

  1. a School of Instrument Science and Opto-Electronics Engineering, Science and Technology on Inertial Laboratory, Beihang University, Beijing 100191, China;
    b School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China
  • Received:2014-11-03 Revised:2014-12-24 Online:2015-06-05 Published:2015-06-05
  • Contact: Wang Tao E-mail:wangtao@buaa.edu.cn
  • About author:07.55.Ge; 07.55.-w; 41.20.Gz; 32.60.+i
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 61227902, 61374210, and 61121003).

摘要: A method of measuring in-situ magnetic field gradient is proposed in this paper. The magnetic shield is widely used in the atomic magnetometer. However, there is magnetic field gradient in the magnetic shield, which would lead to additional gradient broadening. It is impossible to use an ex-situ magnetometer to measure magnetic field gradient in the region of a cell, whose length of side is several centimeters. The method demonstrated in this paper can realize the in-situ measurement of the magnetic field gradient inside the cell, which is significant for the spin relaxation study. The magnetic field gradients along the longitudinal axis of the magnetic shield are measured by a spin-exchange relaxation-free (SERF) magnetometer by adding a magnetic field modulation in the probe beam's direction. The transmissivity of the cell for the probe beam is always inhomogeneous along the pump beam direction, and the method proposed in this paper is independent of the intensity of the probe beam, which means that the method is independent of the cell's transmissivity. This feature makes the method more practical experimentally. Moreover, the AC-Stark shift can seriously degrade and affect the precision of the magnetic field gradient measurement. The AC-Stark shift is suppressed by locking the pump beam to the resonance of potassium's D1 line. Furthermore, the residual magnetic fields are measured with σ+- and σ--polarized pump beams, which can further suppress the effect of the AC-Stark shift. The method of measuring in-situ magnetic field gradient has achieved a magnetic field gradient precision of better than 30 pT/mm.

关键词: spin-exchange relaxation-free, atomic magnetometer, magnetic field gradient, magnetic shield, AC-Stark shift

Abstract: A method of measuring in-situ magnetic field gradient is proposed in this paper. The magnetic shield is widely used in the atomic magnetometer. However, there is magnetic field gradient in the magnetic shield, which would lead to additional gradient broadening. It is impossible to use an ex-situ magnetometer to measure magnetic field gradient in the region of a cell, whose length of side is several centimeters. The method demonstrated in this paper can realize the in-situ measurement of the magnetic field gradient inside the cell, which is significant for the spin relaxation study. The magnetic field gradients along the longitudinal axis of the magnetic shield are measured by a spin-exchange relaxation-free (SERF) magnetometer by adding a magnetic field modulation in the probe beam's direction. The transmissivity of the cell for the probe beam is always inhomogeneous along the pump beam direction, and the method proposed in this paper is independent of the intensity of the probe beam, which means that the method is independent of the cell's transmissivity. This feature makes the method more practical experimentally. Moreover, the AC-Stark shift can seriously degrade and affect the precision of the magnetic field gradient measurement. The AC-Stark shift is suppressed by locking the pump beam to the resonance of potassium's D1 line. Furthermore, the residual magnetic fields are measured with σ+- and σ--polarized pump beams, which can further suppress the effect of the AC-Stark shift. The method of measuring in-situ magnetic field gradient has achieved a magnetic field gradient precision of better than 30 pT/mm.

Key words: spin-exchange relaxation-free, atomic magnetometer, magnetic field gradient, magnetic shield, AC-Stark shift

中图分类号:  (Magnetometers for magnetic field measurements)

  • 07.55.Ge
07.55.-w (Magnetic instruments and components) 41.20.Gz (Magnetostatics; magnetic shielding, magnetic induction, boundary-value problems) 32.60.+i (Zeeman and Stark effects)