Rydberg Atoms Shed Light on Terahertz Waves
The group of Kevin Weatherill from the Joint Quantum Centre based at Durham has recently used fluorescence from highly-excited "Rydberg" atoms to map out Terahertz waves.
The work, featured in Nature Photonics
demonstrates how Terahertz waves, which are typically very difficult to detect, make Cs atoms emit a green fluorescence. Using a normal digital camera, the group were able to take pictures of the glowing atoms to reveal the pattern of a Terahertz standing wave.
The atoms are prepared using a set of carefully controlled laser beams, allowing the Terahertz waves to drive a transition between two atomic states.
Once the transition is complete, the atoms decay back to the ground state, emitting the light that the camera captures. The signal can even be calibrated, giving an absolute measurement of the Terahertz wave intensity.
The study of Terahertz waves has been a hot topic through the last decade, and it is hoped that applications in security and medical imaging, as well as communications and astronomy might be found.
The new method follows international work on Rydberg microwave electrometry, but contrasts strongly with many of the well established methods for Terahertz imaging.
Hopefully the technique's complementary properties will add a useful instrument to the quickly-growing Terahertz tool-kit.