Absence of Superfluidity in 2D Dipolar Bose Striped Crystals

Abstract

We present results of computer simulations at low temperature of a two-dimensional system of dipolar bosons, with dipole moments aligned at an arbitrary angle with respect to the direction perpendicular to the plane. The phase diagram includes a homogeneous superfluid phase, as well as triangular and striped crystalline phases, as the particle density and the tilt angle are varied. In the striped solid, no phase coherence among stripes and consequently no "supersolid" phase is found, in disagreement with recent theoretical predictions.

Cluster stability driven by quantum fluctuations

“…It is interesting to mention that the lack of global coherence (i.e. meaning the absences of supersolidity) has been also recently noted on systems of striped dipolar bosons [41].…”

Saga of Superfluid Solids

“…Between different droplets or across different filaments there can arise quantum-mechanical particle exchanges allowing for the global phase coherence and a superfluid response. This concerns three-dimensional systems, while for two-dimensional dipolar systems there are indications [200] that there is no phase coherence among stripes, hence no global superfluid properties.…”

Supersolid phase of a spin-orbit-coupled Bose-Einstein condensate: A perturbation approach

“…More recently, the supersolid phase has been identified in a series of experiments with dipolar Bose gases, in the form of linear [14][15][16] and two-dimensional [17,18] droplet arrays; in such systems the investigation of collective modes [19][20][21][22], rotational and superfluid properties [23][24][25], out-of-equilibrium phase coherence effects [26], and the role of temperature [27] represents a very active field of research. Although the above experiments were carried out in three dimensions, the appearance of a stripe phase was also predicted by Monte Carlo calculations in two-dimensional configurations, where the polarization direction of the dipoles is tilted with respect to the axis perpendicular to the plane in which they are confined; however, it is still a subject of debate whether such stripes are superfluid or not [28,29].…”