Fast and non-destructive vector field magnetometry with cold atomic ensembles

This paper reports on a fast, nondestructive and sensitive measurement technique that uses atomic spin precession and non-destructive Faraday rotation probing to measure all three components of the magnetic field with kHz bandwidth. In contrast to other vector magnetometer techniques that modulate an applied magnetic field, here the initial atomic polarization is modulated and the magnetic field components are extracted from the resulting free-induction decay (FID) signal, monitored via paramagnetic Faraday rotation. An ensemble of up to 10⁶ cold ⁸⁷Rb in the F = 1 hyperfine ground state was used and held in an optical trap as the field sensor.