High-precision control of static magnetic field magnitude, orientation, and gradient using optically pumped vapour cell magnetometry

Abstract

An integrated system of hardware and software allowing precise definition of arbitrarily oriented magnetic fields up to |B| = 1 μT within a five-layer Mumetal shield is described. The system is calibrated with reference to magnetic resonance observed between Zeeman states of the 6S F = 4 Cs ground state. Magnetic field definition over the full 4π solid angle is demonstrated with one-sigma tolerances in magnitude, orientation, and gradient of δ|B| = 0.94 nT, δθ = 5.9 mrad, and δ|∇B|=13.0 pT/mm, respectively. This field control is used to empirically map M magnetometer signal amplitude as a function of the static field (B) orientation.

Orientational effects on the amplitude and phase of polarimeter signals in double-resonance atomic magnetometry

“…where A = 3m eq 2,0 S 4(4S 2 +1) . Using the B 0 control, signal demodulation and resonance lineshape fitting described in [15], angular scans of the measured on-resonance signal amplitude R and phase 3-4). We note that our experimental measurements of signal amplitude differ slightly in shape to the predicted distributions, a feature which could be reduced by inclusion of higher-order multipole moments in the model signal calculation.…”

“…The magnitude and orientation of the static field B 0 can be controlled in software, with measured tolerances in field magnitude and orientation of 0.94 nT and 5.9 mrad, respectively. For a detailed description and evaluation of the static field control, see [15].…”

A feed-forward measurement scheme for periodic noise suppression in atomic magnetometry

“…The cell is at the centre of a three-axis Helmholtz coil set which act to compensate the Earth's field and apply arbitrary fields in any orientation 23 . The laser light interacts with the atoms and is subsequently analysed by a half-wave plate.…”

Vector Magnetometry Exploiting Phase-Geometry Effects in a Double-Resonance Alignment Magnetometer

“…The data acquisition system is controlled using a PC (not shown). Figure 2 shows the test system used, and a detailed hardware description can also be found in [25]. A spherical room temperature cell of 28 mm diameter containing 133 Cs [26] is contained within a five-layer mu-metal shield.…”

“…To achieve precise control of B 0 , allowing measurement of orientational effects, the static field generating coils are calibrated by measurement of the Larmor frequency under varying orientations of the applied field. The method for initial coil calibration is described in [25]. For a given application of the applied field B APP , the magnitude of the measured field |B MEAS | = ω L /γ is determined by fitting Equations 6 -9 to the demodulated data R(ω RF ) and φ(ω RF ).…”