New Rydberg-Atom Detector Advances Quantum Spectroscopy Techniques

A team from the Faculty of Physics and the Center for Quantum Optical Technologies at the Center of New Technologies, University of Warsaw, has developed a method for measuring terahertz signals using a novel 'quantum antenna' based on Rydberg atoms.

This development allows for the detection and precise calibration of a terahertz frequency comb, which previously represented a gap in the electromagnetic spectrum. The significance of frequency combs lies in their ability to provide a highly accurate measurement standard, akin to an electromagnetic ruler, essential for various applications including spectroscopy and communication technologies.

Rydberg atoms, with an electron in a high orbit, act as sensitive quantum antennas to external electric fields and can be finely tuned across a wide frequency range. The research team successfully measured the signal emitted by a single terahertz comb tooth for the first time, utilizing a hybrid detection method that includes a radio wave-to-light conversion technique.

This innovative approach combines the sensitivity of photon detection with the calibration capabilities of the Autler-Townes method, allowing for the recording of even weak terahertz signals. The research results indicate that this Rydberg-atom-based sensor can now perform precise frequency comb calibration, operating effectively at room temperature, which significantly reduces costs and enhances the potential for commercialization.

The findings are documented in the journal Optica and are positioned to open new avenues in metrology and the applications of terahertz technologies.