Dynamics and universality in noise driven dissipative systems

TL;DR

This paper studies the non-equilibrium critical states in noise-driven low-dimensional systems, analyzing phase transitions and universal behaviors in Josephson junctions and quantum liquids using renormalization group methods.

Contribution

It introduces a controlled RG analysis of nonlinearities in noise-driven systems, revealing universal crossovers and the impact of effective temperature on phase transitions.

Findings

Universal crossover between superconducting and insulating regimes in Josephson junctions.

Renormalization of dissipation and emergence of effective temperature at second order.

Signatures of non-equilibrium critical states observable in transient dynamics.

Abstract

We investigate the dynamical properties of low dimensional systems, driven by external noise sources. Specifically we consider a resistively shunted Josephson junction and a one dimensional quantum liquid in a commensurate lattice potential, subject to $1/f$ noise. In absence of nonlinear coupling, we have shown previously that these systems establish a non-equilibrium critical steady state [Nature Phys. 6, 806 (2010)]. Here we use this state as the basis for a controlled renormalization group analysis using the Keldysh path integral formulation to treat the non linearities: the Josephson coupling and the commensurate lattice. The analysis to first order in the coupling constant indicates transitions between superconducting and localized regimes that are smoothly connected to the respective equilibrium transitions. However at second order, the back action of the mode coupling on the critical state leads to renormalization of dissipation and emergence of an effective temperature. In the Josephson junction the temperature is parametrically small allowing to observe a universal crossover between the superconducting and insulating regimes. The IV characteristics of the junction displays algebraic behavior controlled by the underlying critical state over a wide range. In the noisy one dimensional liquid the generated dissipation and effective temperature are not small as in the junction. We find a crossover between a quasi-localized regime dominated by dissipation and another dominated by temperature. However since in the thermal regime the thermalization rate is parametrically small, signatures of the non-equilibrium critical state can be seen in transient dynamics.