Noise-induced stabilization of dynamical states with broken time-reversal symmetry

TL;DR

This paper investigates how noise influences the stability of dynamical states in Josephson junctions under high-frequency drive, revealing unexpected temperature-dependent switching behavior due to memory effects.

Contribution

It uncovers the role of memory effects in noise-induced stabilization of dynamical states with broken time-reversal symmetry in Josephson junctions.

Findings

Switching rate shows non-monotonic dependence on temperature.

Memory effects cause deviations from traditional transition rate expectations.

Dynamic state retention influences noise-induced stabilization.

Abstract

Under a high frequency drive, Josephson junctions demonstrate "Shapiro steps" of quantized voltage. These are dynamically stabilized states, in which the phase across the junction locks to the external drive. We explore the stochastic switching between two symmetric steps at $\frac{\hbar\omega}{2e}$ and $-\frac{\hbar\omega}{2e}$. Surprisingly, the switching rate exhibits a pronounced non-monotonicity as a function of temperature, violating the general expectation that transitions should become faster with temperature. We explain this behavior by realizing that the system retains memory of the dynamic state from which it is switching, thereby breaking the conventional simplifying assumptions about separations of time scales.