  Non-Gaussian noise influences many complex out-of-equilibrium systems on a
wide range of scales such as quantum devices, active and living matter, and
financial markets. Despite the ubiquitous nature of non-Gaussian noise, its
effect on activated transitions between metastable states has so far not been
understood in generality, notwithstanding prior work focusing on specific noise
types and scaling regimes. Here, we present a unified framework for a general
class of non-Gaussian noise, which we take as any finite-intensity noise with
independent and stationary increments. Our framework identifies optimal escape
paths as minima of a stochastic action, which enables us to derive analytical
results for the dominant scaling of the escape rates in the weak-noise regime
generalizing the conventional Arrhenius law. We show that non-Gaussian noise
always induces a more efficient escape, by reducing the effective potential
barrier compared to the Gaussian case with the same noise intensity.
Surprisingly, for a broad class of amplitude distributions even noise of
infinitesimally small intensity can induce an exponentially larger escape rate.
As the underlying reason we identify the appearance of discontinuous minimal
action paths, for which escape from the metastable state involves a finite
jump. We confirm the existence of such paths by calculating the prefactor of
the escape rate, as well as by numerical simulations. Our results highlight
fundamental differences in the escape behaviour of systems subject to thermal
and non-thermal fluctuations, which can be tuned to optimize switching
behaviour in metastable systems.
