Off-equilibrium Langevin dynamics of the discrete nonlinear Schroedinger chain

TL;DR

This paper introduces Langevin thermostats for controlling temperature and chemical potential in a 1D nonlinear Schrödinger lattice, analyzing non-equilibrium states and comparing kinetic and microcanonical temperature definitions.

Contribution

It presents novel Langevin thermostats capable of controlling both temperature and chemical potential in a nonlinear Schrödinger lattice, enabling detailed non-equilibrium analysis.

Findings

Effective kinetic temperature matches microcanonical temperature in certain limits.

Non-equilibrium stationary states are characterized in low-temperature and high-density regimes.

Dynamics can be mapped onto a coupled-rotor chain with external torque.

Abstract

Suitable Langevin thermostats are introduced which are able to control both the temperature and the chemical potential of a one-dimensional lattice of nonlinear Schr\"odinger oscillators. The resulting non-equilibrium stationary states are then investigated in two limit cases (low temperatures and large particle densities), where the dynamics can be mapped onto that of a coupled-rotor chain with an external torque. As a result, an effective kinetic definition of temperature can be introduced and compared with the general microcanonical (global) definition.