Localized phase structures growing out of quantum fluctuations in a quench of tunnel-coupled atomic condensates

TL;DR

This paper studies the phase dynamics of two tunnel-coupled 1D atomic condensates after a sudden coupling switch, revealing the formation of quasibreathers due to quantum fluctuation amplification governed by the sine-Gordon model.

Contribution

It demonstrates how quantum fluctuations lead to quasibreather formation in coupled condensates, with lifetime and density depending on initial phase, using exact classical solutions.

Findings

Quantum fluctuations cause quasibreather formation.

Lifetime and density depend on initial phase.

Parametric amplification observed in phase dynamics.

Abstract

We investigate the relative phase between two weakly interacting 1D condensates of bosonic atoms after suddenly switching on the tunnel-coupling. The following phase dynamics is governed by the quantum sine-Gordon equation. In the semiclassical limit of weak interactions, we observe the parametric amplification of quantum fluctuations leading to the formation of breathers with a finite lifetime. The typical lifetime and density of the these 'quasibreathers' are derived employing exact solutions of the classical sine-Gordon equation. Both depend on the initial relative phase between the condensates, which is considered as a tunable parameter.