Creation and detection of nonlinear-Zeeman-effect-free hexadecapole signals*

Due to their high sensitivity atomic magnetometers have been proved to be a valuable tool for measuring ultra-low magnetic fields. Unfortunately, the accuracy of these devices suffers when subjected to larger magnetic fields e.g. geomagnetic fields, when the field to be measured is on the order of a few tens of μT. One major cause for this reduction in accuracy is the nonlinear Zeeman (NLZ) effect. While there exist several means to mitigate the error in magnetic field measurement caused by the NLZ effect, in the present work we demonstrate a signal that is intrinsically NLZ effect free. We propose to acquire a signal that originates only from the marginal magnetic sublevels of 87Rb Fg=2 ground state, namely, m=+/-2. The energy of these magnetic sublevels is strictly linearly dependent on the external magnetic field. We intend to build on previous work [1] where it was demonstrated that by creating Δm=2 coherences (quadrupole moment) leads to a more effective creation of Δm=4 coherences (hexadecapole).

We intend to increase the accuracy of 87Rb atomic magnetometers by completely eliminating the NLZ heading error via the creation of hexadecapole moments (Δm=4 coherences) with a precise sequence of modulation pulses and to improve sensitivity by using fluorescence instead of optical rotation.

References:

[1]    V. M. Acosta et al., Opt. Express, 16, 11423 (2008)