A Room-Temperature Solid-State Maser Amplifier

TL;DR

This paper reports the first continuous-wave room-temperature solid-state maser amplifier using nitrogen-vacancy centers in diamond, achieving key amplification characteristics and noise reduction without cryogenic cooling.

Contribution

It demonstrates a practical room-temperature solid-state maser amplifier with continuous-wave operation, a significant advancement over previous cryogenic systems.

Findings

Achieved room-temperature maser amplification with notable gain and bandwidth.

Demonstrated noise temperature reduction and potential for near-quantum-limited amplification.

Showed spin-based cooling of external circuit noise to cryogenic levels without physical cooling.

Abstract

Masers once represented the state-of-the-art in low noise microwave amplification technology, but eventually became obsolete due to their need for cryogenic cooling. Masers based on solid-state spin systems perform most effectively as amplifiers, since they provide a large density of spins and can therefore operate at relatively high powers. Whilst solid-state masers oscillators have been demonstrated at room temperature, continuous-wave amplification in these systems has only ever been realized at cryogenic temperatures. Here we report on a continuous-wave solid-state maser amplifier operating at room temperature. We achieve this feat using a practical setup that includes an ensemble of nitrogen-vacancy center spins in a diamond crystal, a strong permanent magnet and simple laser diode. We describe important amplifier characteristics including gain, bandwidth, compression power and noise temperature and discuss the prospects of realizing a room-temperature near-quantum-noise-limited amplifier with this system. Finally, we show that in a different mode of operation the spins can be used to cool the system noise in an external circuit to cryogenic levels, all without the requirement for physical cooling.