## Picotesla magnetometry with coherent dark states

### Abstract

We investigate the experimental sensitivity limit of a scalar optical magnetometer based on coherent population trapping on the D2 line of a thermal cesium vapor. We find the expected strong dependence on averaging time, with a detection limit below 4 pT for integration times longer than 1 s, limited by slow drifts of the cell temperature and of the applied test magnetic-field itself. A detailed noise analysis shows that for shorter averaging times the demonstrated limit of about 12 pT/$\sqrt{\rm Hz}$ is dominated by the frequency noise of the laser source. The magnetometer can be operated for real-time detection in flux densities up to at least milliteslas and is robust enough for application outside the laser laboratory

Publisher: EDP Sciences
Year: 2003
DOI identifier: 10.1209/epl/i2001-00245-y
OAI identifier: oai:edpsciences.org:dkey/10.1209/epl/i2001-00245-y