Damping-free collective oscillations of a driven two-component Bose gas in optical lattices

TL;DR

This paper investigates how a driven two-component Bose gas in optical lattices exhibits undamped collective oscillations and laser-induced roton modes, revealing new quantum many-body phenomena with suppressed damping effects.

Contribution

It demonstrates the emergence of undamped collective modes and laser-induced roton excitations in a driven Bose-Einstein condensate within optical lattices, highlighting novel damping suppression mechanisms.

Findings

Collective excitations below the laser-induced gap are undamped.

Laser field induces roton modes with non-zero current.

Landau damping rate is significantly suppressed above the gap.

Abstract

We explore quantum many-body physics of a driven Bose-Einstein condensate in optical lattices. The laser field induces a gap in the generalized Bogoliubov spectrum proportional to the effective Rabi frequency. The lowest lying modes in a driven condensate are characterized by zero group velocity and non-zero current. Thus, the laser field induces roton modes, which carry interaction in a driven condensate. We show that collective excitations below the energy of the laser-induced gap remain undamped, while above the gap they are characterized by a significantly suppressed Landau damping rate.