Dichroism and birefringence optical atomic magnetometer with or without self-generated light squeezing

An atomic magnetometer detects atomic responses to the magnetic field, and its sensitivity is ultimately limited by quantum noise fluctuations. For magnetometers based on nonlinear magneto-optical rotation (NMOR), the possible concurrent generation of light squeezing due to polarization self-rotation complicates the optimization for magnetometer sensitivity. Here, we study NMOR magnetometers with frequency-modulated light in a paraffin coated Rb-87 vapor cell in the low and high power regimes corresponding to situations with and without light squeezing, respectively, with detection observables being different Stokes components reflecting the magnetic-field-induced atomic circular dichroism or birefringence. We found that the overall best sensitivity is achieved in the low power regime when there is no light squeezing and for circular dichroism measurement. We provide a general insight on parameter optimization and the choice of detection observables, from the delicate trade-off between the atomic responses and the noises including the technical and quantum optical noises. Our results could have practical significance in optical atomic magnetometry.

Automated summary

The study investigates NMOR magnetometers and finds that the best sensitivity is achieved in the low power regime with no light squeezing. Insights on parameter optimization and choice of detection observables are provided, emphasizing the delicate trade-off between atomic responses and various noise sources. The results could have practical significance in optical atomic magnetometry.