All-optical magnetometry for NMR detection in a micro-Tesla field and unshielded environment

An all-optical atomic magnetometer is used to detect a proton free-precession signal from a water sample polarized in a 0.7 T field and remotely analyzed in a 4 $\mu T$ field. Nuclear spins are manipulated either by $\pi/2$ pulses or by non-adiabatic rotation. The magnetometer operates at room temperature, in an unshielded environment and has a dual-channel sensor for differential measurements.