Floquet-tuned superfluid-checkerboard competition in dipolar bosons

Chao Zhang, Jin Yang

This dataset contains the data associated with the above-mentioned paper, which has been accepted for publication in Physical Review A.

Julia S. Meyer, Corinna Kollath, Thierry Giamarchi

Jin Yang, Yaghmorassene Hebib, Chao Zhang

We study hard-core dipolar bosons on a square lattice subject to a unidirectional periodic drive that Floquet-engineers anisotropic hopping. Driving along one lattice direction provides a controlled way to suppress transverse tunneling, yielding a kinetically quasi-one-dimensional regime with strongly anisotropic transport within the leading-order high-frequency Floquet effective description. In this limit, the system does not reduce to decoupled chains, due to the long-range in-plane dipolar interaction remains isotropic and couples different chains. Focusing on dipoles polarized perpendicular to the plane, for which the interaction is purely repulsive and isotropic, we use sign-problem-free worm-algorithm quantum Monte Carlo simulations to map the half-filling phase diagram versus kinetic anisotropy and dipolar coupling. We find that increasing kinetic anisotropy systematically lowers the interaction strength required to stabilize checkerboard order, demonstrating that Floquet-induced suppression of transverse motion enhances density ordering. Near the superfluid--checkerboard boundary, finite-size results reveal a narrow transition region where the stiffness drops rapidly while checkerboard correlations rise sharply; Its pronounced sharpening with system size is consistent with a weakly first-order transition rounded by finite-size effects. Away from half filling, on the doped sides of the checkerboard plateau, we identify a narrow checkerboard-supersolid regime with simultaneously finite checkerboard correlations and superfluid stiffness, where the superfluid stiffness is anisotropic but the density pattern is isotropic.

Ippei Danshita, Carlos A. R. Sá de Melo

We perform a stability analysis of superfluid (SF) and supersolid (SS) phases of polarized dipolar bosons in two-dimensional optical lattices at high filling factors and zero temperature, and obtain the phase boundaries between SF, checkerboard SS (CSS), striped SS (SSS), and collapse. We show that the phase diagram can be explored through the application of an external field and the tuning of its direction with respect to the optical lattice plane. In particular, we find a transition between the CSS and SSS phases.

F.W. Cummings, J. S. Herold, J. Sarfatt

C. Zhang, Arghavan Safavi-Naini, Barbara Capogrosso-Sansone

Ultracold gases offer an unprecedented opportunity to engineer disorder and interactions in a controlled manner. In an effort to understand the interplay between disorder, dipolar interactions, and quantum degeneracy, we study two-dimensional hard-core dipolar lattice bosons in the presence of on-site bound disorder. Our results are based on large-scale path-integral quantum Monte Carlo simulations by the worm algorithm. We study the ground-state phase diagram at a fixed half-integer filling factor for which the clean system is either a superfluid at a lower dipolar interaction strength or a checkerboard solid at a larger dipolar interaction strength. We find that, even for weak dipolar interactions, superfluidity is destroyed in favor of a Bose glass at a relatively low disorder strength. Interestingly, in the presence of disorder, superfluidity persists for values of the dipolar interaction strength for which the clean system is a checkerboard solid. At a fixed disorder strength, as the dipolar interaction is increased, superfluidity is destroyed in favor of a Bose glass. As the interaction is further increased, the system eventually develops extended checkerboard patterns in the density distribution. Due to the presence of disorder, though, grain boundaries and defects, responsible for a finite residual compressibility, are present in the density distribution. Finally, we study the robustness of the superfluid phase against thermal fluctuations.