T1: Rotons and quantum droplets in dipolar Bose-Einstein condensates

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Dipole-dipole interactions lead to a wealth of new physics in dipolar Bose-Einstein condensates that recent experiments (especially in projects E1 and E2) are starting to unveil. Two main topics have recently attracted a major attention: dipolar rotons and quantum dipolar droplets. This project will investigate both phenomena, in close collaboration with experiments within the Research Unit. Dipolar rotons, recently created for the first time in project E2, are finite-momentum low-energy excitations. Within this project we will study finite-size effects in the physics of rotons. Moreover, the combination of dipolar roton excitations and quantum stabilization, i.e. the mechanism behind the formation of quantum droplets observed in E1 and E2, is expected to lead to a rich ground-state and finite-temperature physics that we will investigate as well. Remarkably, these two effects may allow for the creation of a supersolid, whose realization and properties will be analyzed. Quantum fluctuations, crucial for quantum stabilization, change radically in lower dimensions. We will explore together with project T2 the interesting case of two-dimensional dipolar condensates, which may allow for the creation of particularly robust quantum droplets. Finally, we will investigate as well the ground-state properties and quantum fluctuations of binary dipolar mixtures, recently created in E2.