Miniature atomic magnetometer integrated with flux concentrators
William C. Griffith, Ricardo Jimenez Martinez, Vishal Shah, Svenja A. Knappe, John E. Kitching
A major limitation on the sensitivity of alkali atomic magnetometers, spin-exchange relaxation, can be completely eliminated by operating at low magnetic field and high alkali density. This allows the miniaturization of atomic magnetometers while retaining exceptional sensitivity. We have previously demonstrated a spin exchange relaxation free magnetometer using a millimeter scale vapor cell that achieved magnetic field sensitivity of 70 fT/Hz1/2. The addition of magnetic flux concentrators around the vapor cell is used to further enhance the magnetic field sensitivity. Although limited at low frequencies by magnetic noise in the concentrator material, for frequencies above 100 Hz we reach a sensitivity of 15 fT/Hz1/2.