Localized Phase Structures Growing Out of Quantum Fluctuations in a Quench of Tunnel-coupled Atomic Condensates

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 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.

Ultracold Atoms Out of Equilibrium

“…In this case, interesting analogies with the dynamics of the early universe [143][144][145] and relativistic thermodynamics [146] have been pointed out. Although it appears far-fetched to expect the full complexity and non-equilibrium dynamics of a high-energy or cosmological quantum field theory to be implemented on a degenerate quantum gas consisting only of a few thousand atoms, doing so may not be necessary.…”

Out-of-equilibrium density dynamics of a quenched fermionic system

“…(19). Two conditions are notable, namely (A) when LC1 bounces precisely n times in the system during the ramp or (B) when it bounces n times and then reaches x = L/2 at t = τ .…”

“…These regimes are controlled by the value of the parameter ∆ q introduced in Eq. (19). In particular, we have that ∆ q 1 ∀q defines the sudden quench limit, while the condition ∆ q 1 ∀q determines the adiabatic one.…”

“…More recently, thanks to the advent of cold atoms [6][7][8] , controllable time evolutions of the parameters, dubbed quantum quenches 9,10 , could be experimentally addressed [11][12][13][14][15][16][17][18] , boosting at the same time the theoretical inspection 9,10,[19][20][21][22][23] . A remarkable result is represented by the sharp distinction between the behavior of non-integrable and integrable systems 10 .…”

Two-mode effective interaction in a double-well condensate

“…On the other hand, as a basic element of matter-wave interferometers, such a double-well configuration represents a good example of control of quantum coherence and entanglement in order to achieve high-precision metrology devices [3]. Being a widespread ingredient for modeling in a diversity of areas, such as quantum computing [4] and cosmology [5], it is of fundamental importance to achieve the best comprotnise between simplicity and accuracy in order to propose a theoretical description for these systems. In this respect, a seemingly good balance between both requirements is represented by the so-called two-mode (TM) model, which has been extensively studied in the last few years [1,[6][7][8][9][10][11].…”