Out of equilibrium many-body expansion dynamics of strongly interacting bosons

TL;DR

This paper investigates the many-body expansion dynamics of strongly interacting bosons in one dimension using first-principles solutions, revealing complex trimodal behavior and the importance of dynamical fragmentation beyond mean-field predictions.

Contribution

The study applies the multiconfigurational time-dependent Hartree method for bosons to accurately capture many-body effects in bosonic expansion dynamics, highlighting phenomena not seen in mean-field models.

Findings

Many-body expansion exhibits trimodal dynamics unlike mean-field unimodal expansion.

Dynamical fragmentation plays a key role in the expansion process.

Two- and three-body densities show correlation holes and delocalization effects.

Abstract

We solve the Schr\"odinger equation from first principles to investigate the many-body effects in the expansion dynamics of one-dimensional repulsively interacting bosons released from a harmonic trap. We utilize the multiconfigurational time-dependent Hartree method for bosons (MCTDHB) to solve the many-body Schr\"odinger equation at high level of accuracy. The MCTDHB basis sets are explicitly time-dependent and optimised by variational principle. We probe the expansion dynamics by three key measures; time evolution of one-, two- and three-body densities. We observe when the mean-field theory results to unimodal expansion, the many-body calculation exhibits trimodal expansion dynamics. The many-body features how the initially fragmented bosons independently spreads out with time whereas the mean-field pictures the expansion of the whole cloud. We also present the three different time scale of dynamics of the inner core, outer core and the cloud as a whole. We analyze the key role played by the dynamical fragmentation during expansion. A Strong evidence of the many-body effects is presented in the dynamics of two- and three-body densities which exhibit correlation hole and pronounced delocalization effect.