Clustered Wigner-crystal phases of cold polar molecules in arrays of one-dimensional tubes

Michael Knap,Martin Ganahl,Erez Berg,Eugene Demler

doi:10.1103/physrevb.86.064501

Abstract

We analyze theoretically polar molecules confined in planar arrays of one dimensional tubes. In the classical limit, if the number of tubes is finite, new types of "clustered Wigner crystals" with increasingly many molecules per unit cell can be stabilized by tuning the in-plane angle between the dipolar moments and the tube direction. Quantum mechanically, these phases melt into distinct "clustered Luttinger liquids." We calculate the phase diagram of the system and study the quantum melting of the clustered phases. We find that the requirements for exploring these phases are reachable in current experiments and discuss possible experimental signatures.

Highlights

Systems with competing long-range interactions often exhibit structures with emergent large length scales
We demonstrate that the anisotropic and longrange character of dipolar interactions leads to new types of clustered crystal phases which appear at intermediate values of the interaction strength
A two-dimensional system which consists of an infinite number of tubes with dipoles aligned in the plane exhibits similar physics: the q = 1 Wigner crystal phase becomes locally unstable for φ > φc

Summary

INTRODUCTION

Systems with competing long-range interactions often exhibit structures with emergent large length scales. Realizing long-range interactions with systems of cold polar molecules[10,11,12,13,14,15] can allow to explore emergent emulsion phases in a highly controllable setting In such systems few-body bound states,[16] trimer liquid phases,[17] and bound solitons[18] have been predicted. We demonstrate that the anisotropic and longrange character of dipolar interactions leads to new types of clustered crystal phases which appear at intermediate values of the interaction strength Quantum mechanically, these phases melt into distinct “clustered Luttinger liquids” characterized by the decay of their densitydensity correlation functions. Our calculations indicate that the clustered phases can be explored under current experimental conditions

EXPERIMENTAL SETUP

CLASSICAL LIMIT

QUANTUM MECHANICAL ANALYSIS

EXPERIMENTAL IMPLICATIONS

CONCLUSIONS AND OUTLOOK