Fig. 1.

Experimental setup (components are not drawn to scale). Water flows from a reservoir inside a 7-kG permanent magnet through the encoding region where there is a Helmholtz coil used to apply AF (≈1 kHz) pulses. The water subsequently flows into a channel with dimensions of ≈1 × 2 × 3 mm³ adjacent to a microfabricated atomic-magnetometer vapor cell containing Cs and 5,000 torr of N₂. The sensor assembly is housed inside of a four-layer set of magnetic shields, only one of which is shown here. (Inset) Photograph of a prototype device before the ITO heaters were installed. The device used for the measurements presented in this work had a larger fluid channel than that pictured here. ECDL, external cavity diode laser; LP, linear polarizer; QWP, quarter wave plate; PD, photodiode.