Elementary excitations of trapped Bose gas in the large-gas-parameter regime

TL;DR

This paper investigates how including higher-order correlation effects alters the collective oscillation frequencies of a trapped Bose gas in the large-gas-parameter regime, extending beyond the standard Gross-Pitaevskii theory.

Contribution

It introduces a higher-order correction to the interatomic correlation energy and applies sum-rule and variational methods to compute modified collective frequencies.

Findings

Higher-order terms significantly affect collective mode frequencies

Corrections are substantial in the large-gas-parameter regime

Methodology combines sum-rule approach with variational ground-state calculations

Abstract

We study the effect of going beyond the Gross-Pitaevskii theory on the frequencies of collective oscillations of a trapped Bose gas in the large gas parameter regime. We go beyond the Gross-Pitaevskii regime by including a higher-order term in the interatomic correlation energy. To calculate the frequencies we employ the sum-rule approach of many-body response theory coupled with a variational method for the determination of ground-state properties. We show that going beyond the Gross-Pitaevskii approximation introduces significant corrections to the collective frequencies of the compressional mode.