Superfluid filaments of dipolar bosons in free space

TL;DR

This paper uses quantum Monte Carlo simulations to explore the phase diagram of dipolar bosons in three dimensions, revealing stable filament phases with anisotropic superfluidity and thermal stability.

Contribution

It provides the first systematic study of filament formation and anisotropic superfluidity in 3D dipolar bosons at zero and finite temperatures.

Findings

Filaments are stabilized at high dipolar interactions and densities.

Superfluidity is highly anisotropic, suppressed orthogonal to filaments.

Filaments remain stable against thermal fluctuations.

Abstract

We systematically investigate the zero temperature phase diagram of bosons interacting via dipolar interactions in three dimensions in free space via path integral Monte Carlo simulations with few hundreds of particles and periodic boundary conditions based on the worm algorithm. Upon increasing the strength of the dipolar interaction and at sufficiently high densities we find a wide region where filaments are stabilized along the direction of the external field. Most interestingly by computing the superfluid fraction we conclude that superfluidity is anisotropic and is greatly suppressed along the orthogonal plane. Finally we perform simulations at finite temperature confirming the stability of filaments against thermal fluctuations and provide an estimate of the superfluid fraction in the weak coupling limit in the framework of the Landau two-fluid model.