Relaxation in an Extended Bosonic Josephson Junction

TL;DR

This paper investigates the relaxation dynamics in an extended bosonic Josephson junction, combining simulations and analytic solutions to understand the transition to phase locking and the effects of confinement.

Contribution

It provides a comprehensive analysis of relaxation processes, including an analytic model for short-time dynamics and insights into nonlinear effects beyond the sine-Gordon model.

Findings

Simulations reproduce experimental relaxation behavior.

Analytic solution describes initial multimode dephasing.

Nonlinear dynamics cause relaxation to phase-locked state.

Abstract

We present a detailed analysis of the relaxation dynamics in an extended bosonic Josephson junction. We show that stochastic classical field simulations using Gross-Pitaevskii equations in three spatial dimensions reproduce the main experimental findings of M. Pigneur et al., Phys. Rev. Lett. 120, 173601 (2018). We give an analytic solution describing the short time evolution through multimode dephasing. For longer times, the observed relaxation to a phase locked state is caused by nonlinear dynamics beyond the sine-Gordon model, induced by the longitudinal confinement potential and persisting even at zero temperature. Finally, we analyze different experimentally relevant trapping geometries to mitigate these effects. Our results provide the basis for future experimental implementations aiming to study nonlinear and quantum effects of the relaxation in extended bosonic Josephson junctions.