Classical Field Models for Multimode Bosonic Tunnelling Junctions

Speaker: Dr Matt Reeves
Affiliation: University of Queensland

Abstract

Ultracold atom experiments allow unprecedented  control over the dynamics of  quantum systems. Developments such as arbitrary optical potential generation and single-site addressing schemes in optical lattices have generated an increased interest in the development of so-called ‘atomtronic’ devices. Such devices aim to develop circuits or sensors that leverage quantum aspects such as quantum coherence or superfluid transport.In atomtronic tunnelling junctions, experiments have observed desirable nonlinear features that are routinely harnessed in traditional semiconductor electronics circuits, including nonequilibrium bistability [1] and negative differential conductivity [2]. However, the nonequilibrium dynamics of these quantum systems poses a challenge for theory, and a cohesive theoretical model which can capture the observed behaviours has not yet been developed.In this talk I will present a theoretical model we have developed to describe the bosonic tunnelling junctions using classical field methods [3]. In contrast to previously developed single-mode approximations, the classical field method is found to quantitatively describe many of the observed tunnelling phenomena, without the need for fitting parameters. Our multimode model suggests the nonequilbrium condensate dynamics occurring locally at each junction site hold several important implications for atomtronic applications and the interpretation of particle transport phenomena.

[1] R Labouvie et al., Phys. Rev. Lett. 115, 050601 (2015)
[2] R. Labouvie et al., Phys. Rev. Lett. 116, 235302(2016)
[3] M. T. Reeves and M. J. Davis, arXiv:2102.02949 (2021)