Observation of Light-Induced Dipole-Dipole Forces in Ultracold Atomic Gases

• Published in: Physical review. X Vol. 12; no. 3; p. 031018
• Main Authors: Maiwöger, Mira, Sonnleitner, Matthias, Zhang, Tiantian, Mazets, Igor, Mallweger, Marion, Rätzel, Dennis, Borselli, Filippo, Erne, Sebastian, Schmiedmayer, Jörg, Haslinger, Philipp
• Format: Journal Article
• Language: English
• Published: College Park American Physical Society 01-07-2022
• Subjects: Atoms & subatomic particles; Clouds; Control theory; Dipole interactions; Feedback loops; Lasers; Light; Light beams; Luminous intensity; Particle density (concentration); Photon scatter; Propagation; Rubidium
• ISSN: 2160-3308; 2160-3308
• DOI: 10.1103/PhysRevX.12.031018

Light-matter interaction is well understood on the single-atom level and routinely used to manipulate atomic gases. However, in denser ensembles, collective effects emerge that are caused by light-induced dipole-dipole interactions and multiple photon scattering. Here, we report on the observation of a mechanical deformation of a cloud of ultracoldRb87atoms due to the collective interplay of the atoms and a homogenous light field. This collective light scattering results in a self-confining potential with interesting features: It exhibits nonlocal properties, is attractive for both red- and blue-detuned light fields, and induces a remarkably strong force that depends on the gradient of the atomic density. Our experimental observations are discussed in the framework of a theoretical model based on a local-field approach for the light scattered by the atomic cloud. Our study provides a new angle on light propagation in high-density ensembles and expands the range of tools available for tailoring interactions in ultracold atomic gases.