QUANTUM SENSITIVITY LIMITS OF AN OPTICAL MAGNETOMETER BASED ON ATOMICPHASE COHERENCE

An optical magnetometer based on atomic coherence effects is analyzed using a quantum Langevin approach. The large dispersion of a phase-coh erent atomic medium (''phaseonium'') at a point of vanishing absorptio n is used to detect magnetic level shifts via optical phase measuremen ts in a Mach-Zehnder interferometer with sensitivities potentially sup erior to state-of-the-art devices. Effects of Doppler broadening and f luctuations of the driving field are discussed and a comparison to sta ndard optical-pumping magnetometers is made.