  Many classical scalar field theories possess remarkable solutions: coherently
oscillating, localized clumps, known as oscillons. In many cases, the decay
rate of classical small amplitude oscillons is known to be exponentially
suppressed and so they are extremely long lived. In this work we compute the
decay rate of quantized oscillons. We find it to be a power law in the
amplitude and couplings of the theory. Therefore, the quantum decay rate is
very different to the classical decay rate and is often dominant. We show that
essentially all oscillons eventually decay by producing outgoing radiation. In
single field theories the outgoing radiation has typically linear growth, while
if the oscillon is coupled to other bosons the outgoing radiation can have
exponential growth. The latter is a form of parametric resonance: explosive
energy transfer from a localized clump into daughter fields. This may lead to
interesting phenomenology in the early universe. Our results are obtained from
a perturbative analysis, a non-perturbative Floquet analysis, and numerics.
