  Fock states are the most fundamental quantum states of bosonic fields,
forming an important basis for understanding their quantum dynamics. As energy
and number eigenstates, they have an exactly defined number of quanta, and most
faithfully express the particle nature of fields. These properties make them
attractive for many applications in metrology, and quantum simulation and
information processing. Yet, Fock states are notoriously difficult to generate.
The problem is especially acute in optics, where it is difficult to
deterministically produce Fock states with more than a single photon, let alone
at macroscopic scales. This is in part due to a dearth of mechanisms to produce
large Fock states, as well as the deleterious effects of linear dissipation.
Here, we introduce a new effect in the physics of nonlinear bosons, arising
from the interplay of dissipation and Kerr nonlinearity. In this effect, a
nonlinear resonance is dissipationless when it has a particular number of
quanta (e.g., photons) inside it, and lossy otherwise. This loss, which results
from nonlinear interference, leads to several new quantum statistical effects.
For example, it leads to spontaneous condensation of intensity noise, which may
enable generation of large Fock and extremely photon-number-squeezed states of
light. We also show how this effect has implications for new classes of
optoelectronic devices such as lasers, which can stabilize extremely low-noise
states in an equilibrium between gain and the nonlinear loss that we introduce.
Throughout the text, we present examples of systems that may realize these
effects. In one, we show how the nonlinear dissipation could lead to optical
Fock states of $n=1000$, while in another, we show how conventional laser
architectures could be used to generate macroscopic light ($>10^{12}$ photons)
with nearly 95% less noise than the standard quantum limit.
