Vacuum-squeezing-enhanced micrometer-scale vapor-cell magnetometer

We report on an optical magnetometer enhanced by vacuum-squeezed light, employing an Mx magnetometer based on ⁸⁷Rb vapor in a micrometer-scale cell (approximately 100 µm). Using the well-established polarization self-rotation effect in a room-temperature ⁸⁷Rb vapor cell, we achieve 4 dB of vacuum squeezing within the noise spectral window of 100 Hz to several MHz, corresponding to 4.5-dB squeezing when accounting for optical losses. Leveraging this level of squeezing, we demonstrate a magnetic-field sensitivity of approximately 1 pT√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.