Asymptotic population imbalance of an ultracold bosonic ensemble in a driven double-well

TL;DR

This paper investigates how a driven double-well potential causes a long-term population imbalance in an ultracold bosonic ensemble, revealing quantum and classical effects and controllable asymmetries.

Contribution

It introduces the concept of asymptotic population imbalance in driven bosonic systems and analyzes its dependence on initial states, driving phase, and particle number.

Findings

API can be controlled via driving phase and particle number

Quantum correlations cause deviations from classical predictions

API is sensitive to initial states in few-particle regimes

Abstract

We demonstrate that an ultracold many-body bosonic ensemble confined in an one-dimensional (1D) double well potential exhibits a population imbalance between the two wells at large timescales, when the depth of the wells are modulated by a time-dependent driving force. The specific form of the driving force is shown to break spatial parity and time-reversal symmetries, which leads to such an asymptotic population imbalance (API). The value of the API can be flexibly controlled by changing the phase of the driving force and the total number of particles. While the API is highly sensitive to the initial state in the few-particle regime, this dependence on the initial state is lost as we approach the classical limit of large particle numbers. We perform a Floquet analysis in the few-particle regime and an analysis based on a driven classical non-rigid pendulum in the many-particle regime. Although the obtained API values in the many-particle regime agree very well with that obtained in the classical limit, we show that there exists a significant disagreement in the corresponding real-time population imbalance due to quantum correlations.