Off-diagonal correlations in a one-dimensional gas of dipolar bosons

TL;DR

This study uses quantum Monte Carlo simulations to explore how long-range dipolar interactions influence off-diagonal correlations and momentum distribution in one-dimensional bosonic gases, revealing a transition from quasi-condensation to quasi-solidity and a momentum filtering effect.

Contribution

It provides the first detailed analysis of off-diagonal correlations and momentum filtering in 1D dipolar bosons, highlighting the impact of long-range interactions on quantum phases.

Findings

Long-range dipolar interactions suppress quasi-condensation.

Momentum distribution exhibits sharp kinks at specific wavevectors.

A momentum filtering effect can be tuned by atom density.

Abstract

We present a quantum Monte Carlo study of the one-body density matrix (OBDM) and the momentum distribution of one-dimensional dipolar bosons, with dipole moments polarized perpendicular to the direction of confinement. We observe that the long-range nature of the dipole interaction has dramatic effects on the off-diagonal correlations: although the dipoles never crystallize, the system goes from a quasi-condensate regime at low interactions to a regime in which quasi-condensation is discarded, in favor of quasi-solidity. For all strengths of the dipolar interaction, the OBDM shows an oscillatory behavior coexisting with an overall algebraic decay; and the momentum distribution shows sharp kinks at the wavevectors of the oscillations, $Q = \pm 2\pi n$ (where $n$ is the atom density), beyond which it is strongly suppressed. This \emph{momentum filtering} effect introduces a characteristic scale in the momentum distribution, which can be arbitrarily squeezed by lowering the atom density. This shows that one-dimensional dipolar Bose gases, realized e.g. by trapped dipolar molecules, show strong signatures of the dipolar interaction in time-of-flight measurements.