Vector magnetometry based on electromagnetically induced transparency in linearly polarized light

We develop a generalized principle of electromagnetically induced transparency (EIT) vector magnetometry based on high-contrast EIT resonances and the symmetry of atom-light interaction in the linearly polarized bichromatic fields. Operation of such vector magnetometer on the $D_1$ line of ${}^{87}\mathrm{Rb}$ has been demonstrated. The proposed compass-magnetometer has an increased immunity to shifts produced by quadratic Zeeman and ac-Stark effects, as well as by atom-buffer gas and atom-atom collisions. In our proof-of-principle experiment the detected angular sensitivity to magnetic field orientation is ${10}^{-3}$ deg/Hz${}^{1/2}$, which is limited by laser intensity fluctuations, light polarization quality, and magnitude of the magnetic field.

Figure 1

Pure $\Lambda$ systems at the $D_1$ line of ${}^{87}\mathrm{Rb}$; nonsensitive (a) and sensitive (b) to magnetic field. Here we do not show Zeeman shifts for upper hyperfine levels with $F_e=1,2$.

Figure 2

EIT resonance transmission. Solid line: The case $\mathbf{e}\parallel \mathbf{n}$. The central resonance corresponds to the ${\Lambda }_1$ and ${\Lambda }_2$ schemes [Fig. 1a]. This resonance has 120-kHz width and $~60\%$ transmission. Dashed line: The case $\mathbf{e}\perp \mathbf{n}$. The magnetic field has magnitude 1 G; the angle between $\mathbf{B}$ and $\mathbf{k}$ equals ${20}^{°}$.

Figure 3

Orientation of the magnetic field $\mathbf{B}$, wave vector $\mathbf{k}$, and polarization $\mathbf{e}$ of the optical field.

Figure 4

The schematic of the experimental setup.

Figure 5

The dependence of the EIT-resonance amplitude $A_{\mathbf{k}}$($\phi$) for the ${}^{87}\mathrm{Rb}$ cell transmission on the angle $\phi$ between $\mathbf{e}$ and $\mathbf{n}$. Angles between $\mathbf{B}$ and $\mathbf{k}$ are shown on the right side of each curve (both vectors lie in the horizontal plane).

Figure 6

The lock-in amplifier output at $0.1^{°}$ angle step variation of the magnetic field direction. The magnetic field magnitude is 1 G, and the angle between magnetic field and wave vector is varied near ${90}^{°}$.

Figure 7

Compass sensitivity versus magnetic field magnitude.