Non-Linear Oscillations in Room Temperature Masers

The recent realization of a continuous-wave room temperature maser, using NV⁻ centers in diamond pumped by a 532 nm laser [1], is a promising platform for novel research and development in the areas of signal amplification, timekeeping and sensing. Typically, for such applications a maser oscillator is operated in a linear response regime. For masing, the NV⁻ spin ensemble is pumped into a non-equilibrium state and, for strong enough pump rates, can also be driven into a non-linear regime. Maser oscillation changes dramatically, exhibiting a frequency-comb like spectrum, instead of a single narrow frequency mode. Studying non-linear behavior in room temperature solid-state masers can lead to new pathways of quantum sensing.

We present an NV⁻ center maser system and experimentally characterize the transition from linear to non-linear maser oscillations, via frequency and time domain analysis. A feature for non-linear behavior is bifurcation. Here, the inhomogeneous broadened spin distribution experiences bifurcation. The dynamics can be modelled numerically through a quantum master equation with Lindbladian dissipators and is in excellent agreement with the experimental data. We discuss individual features of the non-linear dynamics and their potential applications.



[1] Jonathan D. Breeze et al., Nature, Volume 555, 493, 2018