Splitting in the Excitation Spectrum of A Bose-Einstein Condensate Undergoing Strong Rabi Oscillations

TL;DR

This paper investigates the splitting in the excitation spectrum of a Bose-Einstein condensate under strong Rabi oscillations, combining experimental measurements with theoretical models to understand the energy gap formation.

Contribution

It provides a combined experimental and theoretical analysis of spectral splitting in a driven condensate, linking it to band structure effects in an optical lattice.

Findings

Spectral splitting observed experimentally matches numerical solutions.

The splitting corresponds to the energy gap at the Brillouin zone boundary.

Band theory explains the observed excitation spectrum features.

Abstract

We report on a measurement of splitting in the excitation spectrum of a condensate driven by an optical travelling wave. Experimental results are compared to a numerical solution of the Gross Pitaevskii equation, and analyzed by a simple two level model and by the more complete band theory, treating the driving beams as an optical lattice. In this picture, the splitting is a manifestation of the energy gap between neighboring bands that opens on the boundary of the Brillouin zone.