Description
Coherent heterodyne detection methods present an opportunity for improved sensitivity in quantum sensing. Four wave mixing is a commonly used spectroscopic technique, with limited previous applications in magnetometry.
Using alkali vapour in a double lambda configuration we perform four wave mixing over the hyperfine states. By beating the probe and generated conjugate beams together at a high bandwidth photodetector, the magnetic field can be measured from the beat frequency.
The technique is viable for all alkali atoms, however we demonstrate it with sodium vapour, using a rhodamine 590 dye laser. Sodium presents challenges with high absorption and low atomic density, but was readily available in our lab.
The coherent heterodyne measurement is estimated to have a sensitivity of around 1$\textup{pT}/\sqrt{\textup{Hz}}$.
| I am the presenting author | Yes |
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