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Newly developed numerical simulations demonstrate that bosons trapped in a narrow spherical shell can become supersolid: a crystal-like structure which supports frictionless particle flow.
Bubble traps, confining ultracold atoms close to the surface of an ellipsoid, are currently the focus of considerable theoretical and experimental activity. Curvature is important in a variety of fields, from cosmology to biology, and being able to measure its effects on the properties of many-body quantum systems opens new and exciting avenues of investigation.
Experiments so far have focused on weak interactions between the atoms; they have been performed in space to contrast the effects of gravity, which causes particles to collapse to the bottom of the bubble trap.
In this work, strongly-interacting bosons are considered instead. Simulations show that a supersolid can arise in a spherical geometry for two different interactions: in particular, soft-core interactions lead to a homogeneous arrangement of clusters on the sphere, which for small radii takes the shape of a (semi)regular polyhedron; conversely, a dipolar interaction leads to the formation of a supersolid ribbon of clusters around the equator. Bringing curvature and supersolidity together for the first time, these results stimulate further studies of the influence of curved confinement on strongly-interacting many-body systems.
Bubble traps, confining ultracold atoms close to the surface of an ellipsoid, are currently the focus of considerable theoretical and experimental activity. Curvature is important in a variety of fields, from cosmology to biology, and being able to measure its effects on the properties of many-body quantum systems opens new and exciting avenues of investigation.
Experiments so far have focused on weak interactions between the atoms; they have been performed in space to contrast the effects of gravity, which causes particles to collapse to the bottom of the bubble trap.
In this work, strongly-interacting bosons are considered instead. Simulations show that a supersolid can arise in a spherical geometry for two different interactions: in particular, soft-core interactions lead to a homogeneous arrangement of clusters on the sphere, which for small radii takes the shape of a (semi)regular polyhedron; conversely, a dipolar interaction leads to the formation of a supersolid ribbon of clusters around the equator. Bringing curvature and supersolidity together for the first time, these results stimulate further studies of the influence of curved confinement on strongly-interacting many-body systems.
Credit: Matteo Ciardi and Fabio Cinti (Università di Firenze); Giuseppe Pellicane and Santi Prestipino (Università di Messina).