Masers are widely used for precision time-keeping and sensing applications. However, conventional maser systems are bulky and need to be cooled to low temperatures, which makes them costly. In 2021, EQUS’ Translational Research Program awarded $50,000 to Master’s student Lyra Cronin to build a compact, frequency-tunable, room-temperature maser platform using nitrogen–vacancy centres in diamond, with applications in time-keeping and defence.

The team developed an experimental set-up for a tunable nitrogen–vacancy microwave amplifier that incorporates a microwave cavity with a strong magnetic field generated by permanent rare-earth magnets. This set-up also enables optical access for laser pumping and fluorescence collection, and incorporates automated fine-grain control of position and rotation in a repeatable and reliable way. The team also simulated different photoniccrystal microwave cavity designs to maximise the coupling between the nitrogen–vacancy ensemble and the cavity. They developed a radio-frequency antenna and investigated the use of radio-frequency technologies as couplings for the microwave cavity.

Lyra is now a PhD student, and received a Defence Innovation Network NSW PhD top-up scholarship to continue work on the maser. The team will work to demonstrate amplification, and to manufacture the simulated cavities and incorporate them into a design more suitable for miniaturisation (on-chip integration), with the ultimate goal of making the technology commercially feasible. The components designed as part of this project and quick prototyping with 3D printing will also benefit further work with new cavity designs.

Published in the 2023 EQUS Annual Report