Vacuum squeezing enhanced micrometer scale vapor cell magnetometer

Abstract: We report on an optical magnetometer enhanced by vacuum-squeezed light, employing an Mx magnetometer based on $^{87}$Rb vapor in a micrometer-scale cell (~100 $\mu$m). Using the well-established polarization self-rotation effect in a room-temperature $^{87}$Rb vapor cell, we achieve -3 dB of vacuum squeezing within the noise spectral window of 100 Hz to several MHz, corresponding to 3.5 dB squeezing when accounting for optical losses. Leveraging this level of squeezing, we demonstrate a magnetic field sensitivity of approx. 1 pT$/$$\sqrt{Hz}$. The combination of vacuum-squeezed light and micrometer-scale vapor cells paves the way for compact, low-power-consumption atomic sensors with enhanced performance.