A dark-state-magnetometer

The aim of this project is to exploit the coherent population trapping effect from atomic physics in a completely new type of magnetometer. The idea of exploiting the coherent population trapping effect in a magnetometer was proposed for the first time in 1998. The measuring principle which it is here proposed to develop (a patent protecting the idea is in preparation in cooperation with TU-Graz 1 ) differs significantly from the original idea in that two dark-resonances are simultaneously coupled. The new magnetometer will be unique in terms of having a very high resolution over a very large field range: 1 ppm or even better in a field range of 1 Gauss down to 100 nGauss (0.1 mT ... 10 pT). This is at least three orders of magnitude higher than that of fluxgate magnetometers commonly used in this field range. Furthermore the magnetometer here proposed will have a significantly better drift stability than existing devices and finally it will be very compact (battery driven with dimensions of the order of 200x100x100 mm). Hence this project will open the possibility of manufacturing a cheap instrument, unsurpassed in terms of accuracy and versatility. The potential applications of the proposed magnetometer are numerous. The most important is perhaps the detection of landmines. It should be possible eventually to make a device which is more sensitive than existing mine detectors based on Flux-gate magnetometers. It might even be possible to create a device which can detect "unmagnetic" landmines (mines made out of plastic). It should be emphasised however that at the present stage this latter application cannot be guaranteed. Further applications include the detection of micro-variations in the earth magnetic field. No device presently available (scientific or commercially) can carry out such accurate measurements at present. Variations in the earth magnetic field are monitored to aid the predictions of earthquakes, volcanic eruptions and tsunamies2 . 1 For further information please contact Frau Priv. Doc. Dr. Ursula Diefenbach, Intellectual Property Management TU-Graz. 2 The proposer wishes to emphasize that he does not want to convey the impression that he is trying to profit from a disaster. These ideas were not developed with tsunamies in mind however, it turns out that changes in the earth magnetic fields are indeed important for tsunamie predictions and hence it should be included as a potential application.