Continuous configuration-interaction for condensates in a ring

TL;DR

This paper introduces a continuous configuration-interaction method for ring-shaped condensates, improving ground-state energy estimates over traditional approaches and providing insights into excited states.

Contribution

The paper presents a novel continuous configuration-interaction approach that yields lower energy solutions for condensates in a ring, surpassing the Gross-Pitaevskii approximation.

Findings

Energy lower than Gross-Pitaevskii solution

Energy approaches or surpasses many-body diagonalization results

Implications for excited state analysis

Abstract

A continuous configuration-interaction approach for condensates in a ring is introduced. In its simplest form this approach utilizes for attractive condensates the Gross-Pitaevskii symmetry-broken solution and arrives at a ground-state of correct symmetry. Furthermore, the energy found is {\it lower} than the Gross-Pitaevskii one and, with increasing number of particles and/or strength of inter-particle interaction, is even {\it lower} than that accessed by tractable diagonalization of the many-body Hamiltonian. Implications also to excited states are briefly discussed.