Supersolid phases of lattice dipoles tilted in three-dimensions

TL;DR

This paper uses quantum Monte Carlo simulations to explore the rich phase diagram of dipolar bosons in a 2D lattice, revealing various supersolid and solid phases, including novel cluster and grain-boundary superfluids, depending on dipole orientation.

Contribution

It introduces a comprehensive analysis of phase diagrams for tilted 3D dipoles in a 2D lattice, discovering new supersolid phases and superfluid behaviors not previously reported.

Findings

Identification of checkerboard and stripe supersolids

Discovery of a cluster supersolid with horizontal particle clusters

Observation of grain-boundary superfluid regions

Abstract

By means of quantum Monte Carlo simulations we study phase diagrams of dipolar bosons in a square optical lattice. The dipoles in the system are parallel to each other and their orientation can be fixed in any direction of the three-dimensional space. Starting from experimentally tunable parameters like scattering length and dipolar interaction strength, we derive the parameters entering the effective Hamiltonian. Depending on the direction of the dipoles, various types of supersolids (e.g. checkerboard, stripe) and solids (checkerboard, stripe, diagonal stripe, and an incompressible phase) can be stabilized. Remarkably, we find a cluster supersolid characterized by the formation of horizontal clusters of particles. These clusters order along a direction at an angle with the horizontal. Moreover, we find what we call a grain-boundary superfluid. In this phase, regions with solid order are separated by extended defects -- grain boundaries -- which support superfluidity. We also investigate the robustness of the stripe supersolid against thermal fluctuations. Finally, we comment on the experimental realization of the phases found.