New classes of systematic effects in gas spin co-magnetometers

Atomic co-magnetometers are widely used in precision measurements searching for spin interactions beyond the Standard Model. We describe a new $^3$He-$^{129}$Xe co-magnetometer probed by Rb atoms and use it to identify two general classes of systematic effects in gas co-magnetometers, one associated with diffusion in second-order magnetic field gradients and another due to temperature gradients. We also develop a general and practical approach for calculating spin relaxation and frequency shifts due to arbitrary magnetic field gradients and confirm it experimentally.Comment: 5 pages, 4 figure

Spin dynamic response to a time dependent field

The dynamic response of a parametric system constituted by a spin precessing in a time dependent magnetic field is studied by means of a perturbative approach that unveils unexpected features, and is then experimentally validated. The first-order analysis puts in evidence different regimes: beside a tailorable low-pass-filter behaviour, a band-pass response with interesting potential applications emerges. Extending the analysis to the second perturbation order permits to study the response to generically oriented fields and to characterize several non-linear features in the behaviour of such kind of systems.Comment: 13 pages, 7 figures, 52 references. Accepted for publication in Applied Physics

Multichannel optical atomic magnetometer operating in unshielded environment

A multi-channel atomic magnetometer operating in an unshielded environment is described and characterised. The magnetometer is based on D1 optical pumping and D2 polarimetry of Cs vapour contained in gas-buffered cells. Several technical implementations are described and discussed in detail. The demonstrated sensitivity of the setup is 100fT/Hz^1/2 when operating in the difference mode.Comment: 9 pages, 5 figures, appearing in Appl.Phys.

All-Optical Nonzero-Field Vector Magnetic Sensor For Magnetoencephalography

We present the concept and the results of an investigation of an all-optical vector magnetic field sensor scheme developed for biological applications such as non-zero field magnetoencephalography and magnetocardiography. The scheme differs from the classical two-beam Bell-Bloom scheme in that the detecting laser beam is split into two beams, which are introduced into the cell in orthogonal directions, and the ratio of the amplitudes of the magnetic resonance signals in these beams and their phase difference are measured; strong optical pumping from the lower hyperfine level of the ground state ensures the resonance line narrowing, and detection in two beams is carried out in a balanced schemes by measuring the beam polarization rotation. The proposed sensor is compact, resistant to variations of parameters of laser radiation and highly sensitive to the angle of deflection of the magnetic field vector - with an estimated scalar sensitivity of the order of 16 fT/Hz1/2 in 8x8x8 mm3 cell, an angular sensitivity of 4x10-7 rad, or 0.08'', was demonstrated

Restoring Narrow Linewidth to a Gradient-Broadened Magnetic Resonance by Inhomogeneous Dressing

We study the possibility of counteracting the line-broadening of atomic magnetic resonances due to inhomogeneities of the static magnetic field by means of spatially dependent magnetic dressing, driven by an alternating field that oscillates much faster than the Larmor precession frequency. We demonstrate that an intrinsic resonance linewidth of 25~Hz that has been broadened up to hundreds Hz by a magnetic field gradient, can be recovered by the application of an appropriate inhomogeneous dressing field. The findings of our experiments may have immediate and important implications, because they facilitate the use of atomic magnetometers as robust, high sensitivity detectors in ultra-low-field NMR imaging.Comment: 9 pages, 7 figures, 33 refs. This is the unedited versio

How to build a magnetometer with thermal atomic vapor: A tutorial

This article is designed as a step-by-step guide to optically pumped magnetometers based on alkali atomic vapor cells. We begin with a general introduction to atomic magneto-optical response, as well as expected magnetometer performance merits and how they are affected by main sources of noise. This is followed by a brief comparison of different magnetometer realizations and an overview of current research, with the aim of helping readers to identify the most suitable magnetometer type for specific applications. Next, we discuss some practical considerations for experimental implementations, using the case of an $M_z$ magnetometer as an example of the design process. Finally, an interactive workbook with real magnetometer data is provided to illustrate magnetometer-performance analysis.Comment: 52 pages, 9 figures, 3 tables. Submitted to New Journal of Physics as an invited review/tutorial for the special issue "Focus on Hot Atomic Vapors". Minor content and language errors corrected in v