Formation of granular structures in trapped Bose-Einstein condensates under oscillatory excitations

Abstract

We present experimental observations and numerical simulations of nonequilibrium spatial structures in a trapped Bose-Einstein condensate subject to oscillatory perturbations. In experiment, first, there appear collective excitations, followed by quantum vortices. Increasing the amount of the injected energy leads to the formation of vortex tangles representing quantum turbulence. We study what happens after the regime of quantum turbulence, with increasing further the amount of injected energy. In such a strongly nonequilibrium Bose-condensed system of trapped atoms, vortices become destroyed and there develops a new kind of spatial structure exhibiting essentially heterogeneous spatial density. The structure reminds fog consisting of high-density droplets, or grains, surrounded by the regions of low density. The grains are randomly distributed in space, where they move. They live sufficiently long time to be treated as a type of metastable objects. Such structures have been observed in nonequilibrium trapped Bose gases of ${}^{87}$Rb, subject to the action of alternating fields. Here we present experimental results and support them by numerical simulations. The granular, or fog structure is essentially different from the state of wave turbulence that develops after increasing further the amount of injected energy.

Latex file, 14 pages, 5 figures

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Cited by in corpus (9)

• Modulational instability, inter-component asymmetry and formation of quantum droplets in one-dimensional binary Bose gases
• Realization of inverse Kibble-Zurek scenario with trapped Bose gases
• Vortex reconnections in anisotropic trapped three-dimensional Bose-Einstein condensates
• Quantum turbulence in Bose-Einstein condensates: present status and new challenges ahead
• Solvable model of a generic driven mixture of trapped Bose-Einstein condensates and properties of a many-boson Floquet state at the limit of an infinite number of particles
• Numerical simulation of nonequilibrium states in a trapped Bose-Einstein condensate
• Models of Mixed Matter
• Optical lattice with heterogeneous atomic density
• Characteristic quantities for nonequilibrium Bose systems