Parametric instabilities of interacting bosons in periodically-driven 1D optical lattices

TL;DR

This paper investigates parametric instabilities in weakly-interacting Bose-Einstein condensates subjected to strong periodic driving in optical lattices, revealing how such instabilities can cause rapid condensate destruction and impact Floquet-engineering.

Contribution

It experimentally demonstrates the existence of parametric instabilities in driven Bose-Einstein condensates, highlighting their role in limiting the stability of Floquet-engineered many-body quantum systems.

Findings

Parametric instabilities cause rapid growth of collective excitations.

Instabilities are prominent in systems with weak transverse harmonic confinement.

Experimental momentum-resolved measurements confirm the presence of these instabilities.

Abstract

Periodically-driven quantum systems are currently explored in view of realizing novel many-body phases of matter. This approach is particularly promising in gases of ultracold atoms, where sophisticated shaking protocols can be realized and inter-particle interactions are well controlled. The combination of interactions and time-periodic driving, however, often leads to uncontrollable heating and instabilities, potentially preventing practical applications of Floquet-engineering in large many-body quantum systems. In this work, we experimentally identify the existence of parametric instabilities in weakly-interacting Bose-Einstein condensates in strongly-driven optical lattices through momentum-resolved measurements. Parametric instabilities can trigger the destruction of weakly-interacting Bose-Einstein condensates through the rapid growth of collective excitations, in particular in systems with weak harmonic confinement transverse to the lattice axis.