Optically Driven Spin Precession

Magnetic field imaging with microfabricated optically-pumped magnetometers

“…Our imaging array can also operate in the total-field mode, which is best suited for applications at Earth's field [11]. We have previously demonstrated that sensors built in similar fashion can operate in the total-field mode by optically driving spin precession on resonance, i.e., so-called Bell-Bloom magnetometer [26]. In that work, we demonstrated sensitivities below 3 pT/Hz 1/2 and bandwidths of 1 kHz [27].…”

Optical magnetometry

“…A weak magnetic field oscillating at the Larmor frequency is commonly used for this purpose [2,10]. Other techniques include application of microwave fields [15] and all-optical excitation using various types of modulation of the light beams: intensity, frequency or polarization [3,7]. Quantum mechanics sets fundamental limits on the best sensitivity that can be achieved in a magnetic-field measurement using atoms.…”

“…Several mechanisms of comparable importance have been identified for such relaxation [30], but some aspects of this process remain poorly understood [31]. The measured spin-destruction cross-sections are smaller for lighter alkali-metal atoms and result in a fundamental limit on the sensitivity of a K magnetometer of about 10 −17 V −1/2 T/Hz 1/2 [32], where V is the active volume of the sensor in cm 3 .…”

“…It has been nearly half a century since the techniques of measuring magnetic fields using optical pumping and probing of alkali atoms were realized in the pioneering work of Dehmelt [1], Bell and Bloom [2,3] and further developed by Cohen-Tannoudji, Dupon-Roc, and co-workers, see, for example, Refs. [4,5].…”

Polarization oscillations of coupled laser beams in an optically pumped atomic vapour

“…This polarization of the angular momentum substates leads to a long-lived optical anisotropy which modulates the polarization of a transmitted laser beam [ 5,6 ]. On the other hand, precessing ground state magnetization can be produced very efficiently by modulated optical pumping [7][8][9]. The feedback of transmitted light into the atomic medium by the optical cavity leads therefore to a nonlinear coupling between atoms and radiation and, for a range of control parameters, to instabilities like self-pulsing or chaos.…”