Non-Equilibrium Quantum Dynamics of Ultra-Cold Atomic Mixtures: the Multi-Layer Multi-Configuration Time-Dependent Hartree Method for Bosons

TL;DR

This paper introduces a multi-layer multi-configuration time-dependent Hartree method for bosons, enabling efficient simulation of non-equilibrium quantum dynamics in multi-species ultracold atomic systems, capturing correlations accurately.

Contribution

The paper presents a novel ab initio computational method with a multi-layer structure to model intra- and inter-species correlations in bosonic mixtures.

Findings

Demonstrated the method's efficiency in simulating correlated tunneling dynamics.

Showed how population imbalances evolve and depend on inter-species coupling.

Observed bosonic bunching tendencies influenced by species interactions.

Abstract

We develop and apply the multi-layer multi-configuration time-dependent Hartree method for bosons, which represents an ab initio method for investigating the non-equilibrium quantum dynamics of multi-species bosonic systems. Its multi-layer feature allows for tailoring the wave function ansatz in order to describe intra- and inter-species correlations accurately and efficiently. To demonstrate the beneficial scaling and the efficiency of the method, we explore the correlated tunneling dynamics of two species with repulsive intra- and inter-species interactions, to which a third species with vanishing intra-species interaction is weakly coupled. The population imbalances of the first two species can feature a temporal equilibration and their time-evolution significantly depends on the coupling to the third species. Bosons of the first and of the second species exhibit a bunching tendency, whose strength can be influenced by their coupling to the third species.