Saarland University and UCL Generate a 10-Tooth Microwave Frequency Comb From a Room-Temperature Diamond Maser at 9.23 GHz, arXiv 19 August 2026

Four authors from Saarland University and University College London pumped a nitrogen-vacancy diamond maser past its ordinary threshold and watched its single 9.23 gigahertz line turn into a microwave frequency comb of up to 10 teeth spaced 3.8 kilohertz apart, at room temperature and without a vacuum chamber. We read what a cryogen-free comb source would mean for GPS-independent timing and for the low-noise amplification a receiver front end depends on, why the work is dual-use, and why the missing stability measurement keeps this room-temperature diamond maser at a bench proof of concept.