Universal breakdown of Kibble-Zurek scaling in fast quenches across a phase transition

The crossing of a continuous phase transition in finite time gives rise to the formation of topological defects described by the Kibble-Zurek mechanism (KZM) in the limit of slow quenches. The KZM predicts a universal power-law scaling of their density with the quench time in which the transition is crossed. We focus on the deviations from KZM experimentally observed in rapid quenches and establish their universality. While KZM scaling holds below a critical quench rate, for faster quenches the defect density and the freeze-out time become independent of the quench rate and exhibit a universal power-law scaling with the final value of the control parameter. These predictions are verified in paradigmatic scenarios using a $\phi^4$-theory and a model of a strongly-coupled superconducting ring.Comment: 7+1 pp, 5 figure