Absence of Landau damping in driven three-component Bose-Einstein condensate in optical lattices

TL;DR

This paper investigates a three-component Bose-Einstein condensate in optical lattices driven by laser fields, revealing a laser-induced energy gap and suppression of Landau damping of collective modes due to laser-induced roton modes.

Contribution

The study provides exact analytical solutions for the energy spectrum and elementary excitations, highlighting the effects of laser driving on damping mechanisms in multi-component BECs.

Findings

Laser fields induce a gap in the Bogoliubov spectrum.

Landau damping is suppressed above the energy gap.

Laser-induced roton modes carry damping above the gap.

Abstract

We explore the quantum many-body physics of a three-component Bose-Einstein condensate (BEC) in an optical lattices driven by laser fields in $V$ and $\Lambda$ configurations. We obtain exact analytical expressions for the energy spectrum and amplitudes of elementary excitations, and discover symmetries among them. We demonstrate that the applied laser fields induce a gap in the otherwise gapless Bogoliubov spectrum. We find that Landau damping of the collective modes above the energy of the gap is carried by laser-induced roton modes and is considerably suppressed compared to the phonon-mediated damping endemic to undriven scalar BECs.