Subpicotesla Scalar Atomic Magnetometer with a Microfabricated Cell

Abstract: We demonstrated a scalar atomic magnetometer using a micro-fabricated Cs vapor cell. The atomic spin precession is driven by an amplitude-modulated circularly-polarized pump laser resonant on D1 transition of Cs atoms and detected by an off-resonant linearly-polarized probe laser using a balanced polarimeter setup. Under a magnetic field with amplitude in the Earth's magnetic field range, the magnetometer in the gradiometer mode can reach sensitivities below 150 fT/rt-Hz, which shows that the magnetometer by itself can achieve sub-100 fT/rt-Hz sensitivities. In addition to its high sensitivity, the magnetometer has a bandwidth close to 1 kHz due to the broad magnetic resonance inside the small vapor cell. Our experiment suggests the feasibility of a portable, low-power and high-performance magnetometer which can be operated in the Earth's magnetic field. Such a device will greatly reduce the restrictions on the operating environment and expand the range of applications for atomic magnetometers, such as detection of nuclear magnetic resonance (NMR) in low magnetic fields.