Quantum-enhanced Optical Magnetometer Using Squeezed Light in Atomic Vapor

We have built an optical magnetometer based on the nonlinear Faraday effect in hot Rb vapor and probe this device with both coherent light and polarization-squeezed light. We generate the squeezed light states using the polarization self-rotation effect in Rb vapor, optimized for the highest noise suppression, giving us a system which is allatomic. By probing with polarization-squeezed states of light, the magnetometer sensitivity is enhanced compared to a coherent probe for a certain range of atomic densities in the magnetometer vapor cell. At high densities, interactions of the light probe with the atoms add excess noise to the device and degrade the magnetometer performance.