Atomic Magnetometer Applications

 

1. Remote magnetometry: Measurement of the Earth magnetic field (and its anomalies) and Space magnetometry

Geophysical and Space applications


 

Measurements of the geomagnetic field and its anomalies. These enable:

  1. at a meter scale (a few meters): locating ferromagnetic objects underground or underwater such as unexploded ordnance or abandoned vessels with toxic waste

  2. at a kilometer scale: identification of geological formations containing minerals or oil

  3. at a hundred Km scale: investigating the Earth's outer mantle, the ionic currents in the ocean and the ionospheric dynamo (parameters studied for climate-change models)

  4. at a thousand Km scale: investigating the geodynamo at depths of several thousand kilometers

 

There are also miscellaneous applications in warfare, including the identification of submarines.


 

2. Biomagnetometry (Detection of biomagnetic fields)

 

 


 

3. Detection of Nuclear Magnetic Resonance with Magnetometers

(Includes studies of rocks - petrology)

 

 

> References for Atomic Magnetometer Applications

 

"Magnetometry: Techniques, Recent Developments, Applications"

by Prof. Dmitri Budker

https://www.azoquantum.com/Article.aspx?ArticleID=7

 

 

"Optical Magnetometry"

edited by Dmitry Budker, University of California, Berkeley and Derek F. Jackson Kimball, California State University, East Bay, Cambridge University Press (2013) - Publisher link

Google reference: 

https://www.google.com/search?tbo=p&tbm=bks&q=isbn%3A1107010357

 

 

Figure 1: cover of the book "Optical Magnetometry"

 

Full table of contents: 

http://assets.cambridge.org/97811070/10352/frontmatter/9781107010352_frontmatter.pdf

 

Indicative chapters:

 

Part I Principles and techniques
6 Optical magnetometry with modulated light
12 Magnetic shielding
 
Part II Applications 
13 Remote detection magnetometry 
14 Detection of nuclear magnetic resonance with atomic magnetometers 
15 Space magnetometry
16 Detection of biomagnetic fields
17 Geophysical applications

 

 

 

Optical magnetometry

Budker D., Romalis M., Nature Physics (3), p. 227–234 (2007)

https://www.nature.com/articles/nphys566

 

Source arXiv: https://www.researchgate.net/publication/2177684_Optical_Magnetometry

 

 

 

 

 

 

Remote magnetometry - Measurement of the Earth's magnetic field using mesospheric sodium and Laser Guide Stars (LGS)

Magnetometry with LGS technology

 

In a previous section, we referred to the "Laser Guide Stars". The publication by W. Happer et al (https://www.osapublishing.org/josaa/abstract.cfm?uri=josaa-11-1-263) is considered to be a major reference. W. Happer, a physicist who pioneered spin-polarized spectroscopy and the sodium Laser Guide Stars, had thought of using LGS for Magnetometry but never published on the subject. Below, preceded by a commentary, is the first publication on the subject by a team consisting of members of D. Budker's lab and also scientists of ESO.

 

 

 

"Physicists propose beaming laser at atmospheric sodium to measure global magnetic field"

https://www.sciencedaily.com/releases/2011/02/110214155449.htm

 

 

James M. Higbie, Simon M. Rochester, Brian Patton, Ronald Holzlöhner, Domenico Bonaccini Calia, and Dmitry Budker. Magnetometry with mesospheric sodiumPNAS, February 14, 2011 DOI: 10.1073/pnas.1013641108

 

 

What is the magnetometric sensitivity of the technique?

Excerpt from the publication above and also the book "Optical Magnetometry, edited by Dmitry Budker and Derek F. Jackson Kimball, Cambridge University Press (2013) - Location 7069

 

"The calculated magnetometric sensitivity, which is limited by currently available laser power and may therefore be expected to improve with advances in laser technology, is useful for the envisaged geophysical applications which require measurement of fields, e.g., in the 1–10 nT range for ocean circulation [2] and the tens of nanotesla range for the solar-quiet dynamo [1]; moreover, the dynamic range of the measurement is not subject to any simple physical limit, as the resonance technique works well and with similar sensitivity at any magnetic-field strength. Moreover, the sensitivity of this technique could be further enhanced by as much as five orders of magnitude by reflecting a laser from a rocket- or satellite-borne retroreflector, instead of being limited to the small fraction of fluorescence emitted toward the detecting telescope."

 

10 to the minus 9 enhanced by 5 orders of magnitude is 10 to the minus 14, one order below the femtotesla.
 

Please note that the brain magnetic field is in the order of picotesla and femtotesla (cf. 

http://www.bemri.org/publications/natural-fields/113-environmental-and-biological-magnetic-flux-densities/file.html) and

https://en.wikipedia.org/wiki/Orders_of_magnitude_(magnetic_field))

 

 

 

 

 

 

 

 

"Sodium guide star at Larmor frequency extends geomagnetic studies"

 

Figure 2: Facebook post from Laser Focus World 

https://www.facebook.com/LaserFocusWorld/photos/a.10152444584165298.966977.126899915297/10159992102510298/?type=3&theater.

 

"Researchers at the Shanghai Institute of Optics and Find Mechanics (SIOM) have succeeded in developing a high-power 589 nm sodium laser pulsed at the Larmor frequency in the 200–350 kHz range for remote magnetometry, which translates to analysis of 100-km-scale variations at the ground: https://goo.gl/X4miT4"

 

Cited study at https://www.ncbi.nlm.nih.gov/pubmed/?term=29088161