Catenaa, Monday, December 15, 2025- Scientists at the University of Warsaw have developed a quantum antenna capable of precisely measuring terahertz frequency combs, a region of the electromagnetic spectrum that had remained largely inaccessible.
The breakthrough combines Rydberg atoms and a radio wave-to-light conversion method to detect and calibrate extremely weak terahertz signals at room temperature.
The team from the Faculty of Physics and the Centre for Quantum Optical Technologies used rubidium atoms in highly excited Rydberg states.
These atoms act as quantum antennas, sensitive to external electric fields, and can be tuned to individual frequencies within a terahertz comb.
By converting the terahertz signals into optical photons, researchers achieved high sensitivity using single-photon detectors.
Terahertz radiation, located between microwaves and infrared light, has applications in non-invasive scanning, ultra-fast communications such as 6G, and advanced spectroscopy.
Previously, measuring terahertz frequency combs at the level of individual “teeth” was impossible due to their fast oscillation and incompatibility with conventional electronics or optical methods.
The Warsaw team successfully observed several dozen comb teeth and directly calibrated the comb’s intensity using atomic properties.
This approach provides a self-calibrating, highly accurate measurement system, unlike traditional antennas that require complex lab calibration.
The work, reported in Optica, offers a foundation for room-temperature quantum sensors and reference measurement standards for terahertz technologies.
It could accelerate the development of applications in imaging, communications, and metrology, while significantly lowering costs compared with other quantum systems requiring cryogenic conditions.
