2025/05/09 by Morihiro Ohta, Ching-Ping Lee, Ohta, Morihiro +23
Physics and Astronomy · Computer Science · Materials Science · #Cold Atom Physics and Bose-Einstein Condensates #Quantum Information and Cryptography #Diamond and Carbon-based Materials Research
paper · pdf · doi:10.48550/arxiv.2505.05705
Microwave quantum technologies require amplification of weak signals with minimal added noise at millikelvin temperatures. This stringent demand has been met with superconducting parametric amplifiers. While masers offer another fundamental approach, their dependence on cryogenic operation has historically posed challenges for classical communication technologies -- a barrier that does not apply to microwave quantum technologies. In this work, we demonstrate an ultra-low-noise maser amplifier utilizing impurity spins in diamond at millikelvin temperatures. We achieve power gains exceeding 30 dB, a minimum noise temperature of 0.86 K (corresponding to 2.2 noise photons), and a maximum 1 dB output compression point of -63 dBm at 6.595 GHz. Our results establish masers as viable components of microwave quantum technologies.