Many-body excitation spectra of trapped bosons with general interaction by linear response

TL;DR

This paper extends the linear-response theory for trapped bosons to systems with general interactions, providing numerical benchmarks and a compact representation to facilitate analysis of larger many-body systems.

Contribution

It implements the multiconfigurational time-dependent Hartree for bosons method for general interactions and introduces a compact block-diagonal form for efficient computation.

Findings

Identifies many-body excitations beyond Bogoliubov--de Gennes equations.

Benchmarks against exactly solvable models.

Provides a scalable approach for larger systems.

Abstract

The linear-response theory of the multiconfigurational time-dependent Hartree for bosons method for computing many-body excitations of trapped Bose-Einstein condensates [Phys. Rev. A {\bf 88}, 023606 (2013)] is implemented for systems with general interparticle interaction. Illustrative numerical examples for repulsive and attractive bosons are provided. The many-body linear-response theory identifies the excitations not unraveled within Bogoliubov--de Gennes equations. The theory is herewith benchmarked against the exactly-solvable one-dimensional harmonic-interaction model. As a complementary result, we represent the theory in a compact block-diagonal form, opening up thereby an avenue for treating larger systems.