Optimisation of Nitrogen-Vacancy Spin Ensembles for Room-Temperature Diamond Masers

The microwave-frequency cousins of lasers - known as masers - can be operated as oscillators and amplifiers with quantum-limited noise performance. While conventional masers require high vacuums or cryogenic temperatures to operate, the recent demonstration of a diamond maser that can operate continuously in ambient conditions [1] promises to make the exceptionally low noise of masers widely applicable to a range of new applications in quantum sensing, telecommunications and medical imaging [2].



In order to realise these broad applications it will be necessary to build miniaturised, portable diamond masers that can be readily integrated into existing standards but demonstrations of diamond masers to date have required the bulky electromagnets of Electron Paramagnetic Resonance (EPR) spectrometers to provide a sufficiently homogeneous magnetic field. Here we discuss different strategies for relaxing the homogeneity requirement for the magnetic field by optimising the diamond and characterise the performance of diamond masers employing customised gain media in which the concentrations of 13C nuclei and nitrogen-vacancy spins are varied. We conclude by discussing recent progress in the development of miniaturised diamond masers.

[1] J. D. Breeze et al., Nature 555, 493–496 (2018).

[2] D. M. Arroo et al., Appl. Phys. Lett. 119, 140502 (2021).