We report a photon shot-noise-limited (SNL) optical magnetometer based on amplitude modulated optical rotation using a room-temperature 85Rb vapor in a cell with anti-relaxation coating. The instrument achieves a room-temperature sensitivity of

$70\ {\rm fT}/\sqrt {\mathrm{Hz}}$
70 fT / Hz at 7.6 μT. Experimental scaling of noise with optical power, in agreement with theoretical predictions, confirms the SNL behaviour from 5 μT to 75 μT. The combination of best-in-class sensitivity and SNL operation makes the system a promising candidate for application of squeezed light to a state-of-the-art atomic sensor.

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