Quantom Optics seminar by Georg Bison, Paul Scherrrer Institut

Magnetometry challenges in fundamental science

Many experiments designed to test our understanding of the Universe at a fundamental level (see e.g. [1]), especially those searching for electric dipole moments (EDM) [2], require stable and homogeneous magnetic fields. Statistical and systematic uncertainties in such experiments depend on temporal and spatial variations of the magnetic field and can be the limiting factor in the overall experimental sensitivity. Improving the precision at which such fundamental physics tests can be performed thus poses increasingly demanding challanges for the creation and measurement of highly stable and homogeneous magnetic fields.

Taking the neutron EDM experiment at PSI as an example, the presentation will introduce fundamental physics tests and show how the relevant aspects of the magnetic field can be monitored by a variety of special magnetometer systems based on optically-pumped Cs [3], 199Hg [4], and 3He [5]. The used magnetometer techniques include multi-beam vector readout [6], accurate all-optical field readings, and the readout of precessing 3He spins with Cs OPM [7]. The measurement of magnetic field gradients requires a large number of Cs sensors similar to arrays previously designed for bio-magnetometry [8].


  1. C. Abel et al., Search for Axionlike Dark Matter through Nuclear Spin Precession in Electric and Magnetic Fields, Phys. Rev. X 7.4, (2017).
  2. J.M. Pendlebury et al., Revised Experimental Upper Limit on the Electric Dipole Moment of the Neutron, Phys. Rev. D 92, 092003 (2015).
  3. A. Weis, G. Bison and Z. D. Grujic, Magnetic Resonance Based Atomic Magnetometers, in A. Grosz et al. (Eds.), High Sensitivity Magnetometers, Springer International Publishing, ISBN 978-3-319-34068-5, (2016).
  4. G. Ban et al., Demonstration of sensitivity increase in mercury free spin precession magnetometers due to laser-based readout for neutron electric dipole moment searches, NIM A 896 (2018).
  5. H.-C. Koch et al., Investigation of the intrinsic sensitivity of a 3He/Cs magnetometer. Eur. Phys. J. D 69(11), 262 (2015).
  6. G. Bison et al., Sensitive and stable vector magnetometer for operation in zero and finite fields, Opt. Exp. 26, 17350-59, (2018).
  7. Z.D. Grujic et al., A sensitive and accurate atomic magnetometer based on free spin precession. In: European Physical Journal D 69.5 (2015).
  8. G. Lembke, et al. Optical multichannel room temperature magnetic field imaging system for clinical application. Biomed. Opt. Exp. 5(3), 62–65 (2014).