Two-dimensional supersolid formation in dipolar Bose-Einstein condensates

The long sought-after supersolid phase has recently been observed in dipolar Bose-Einstein condensates, exhibiting global phase coherence and crystalline density structure.  While one-dimensional supersolids may be prepared by quenching the local interaction strength, we find that such a procedure in two dimensions leads to a loss of both phase coherence and crystalline order. We develop a finite-temperature stochastic Gross-Pitaevskii theory that includes beyond-meanfield effects to explore the formation process for 2D supersolids, and find that evaporative cooling directly into the supersolid phase produces a robust supersolid in a circular (pancake-shaped) trap. We then experimentally produce a 2D supersolid in a near-circular trap through such an evaporative procedure. Our work provides insight into the process of supersolid formation in 2D, and defines a realistic path to the formation of large two-dimensional supersolid arrays.