Balancing nonlinear gain and loss automatically generates sub-Poissonian light, through negative feedback, when the gain is significantly reduced (increased) by the addition (subtraction) of a single photon. We show that micromaser trapping states can provide the necessary feedback in the presence of photon loss and, with the addition of external parametric control, realize a photon number on the order of 100 and a Mandel $Q$ parameter of $-0.998$, i.e., number squeezing of 27 dB.

• Received 11 August 2019
• Accepted 22 January 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.063604