On the infrared cutoff for dipolar droplets

TL;DR

This paper revisits the theoretical modeling of quantum fluctuations in dipolar quantum gases, comparing different infrared cutoff schemes to experimental data to improve the understanding of quantum droplet phase boundaries.

Contribution

It introduces alternative cutoff methods for quantum fluctuation calculations and compares their predictions with experimental results, addressing discrepancies in phase boundary predictions.

Findings

Different cutoff schemes affect the predicted phase boundaries.

Comparison reveals limitations of current models.

Proposes refined approaches for better agreement with experiments.

Abstract

The beyond mean-field physics due to quantum fluctuations is often described by the Lee-Huang-Yang (LHY) correction, which can be approximately written as a simple analytical expression in terms of the mean-field employing local density approximation. This model has proven to be very successful in predicting the dynamics in dipolar Bose-Einstein condensates both qualitatively and quantitatively. Yet, a small deviation between experimental results and the theoretical prediction has been observed when comparing experiment and theory of the phase boundary of a free-space quantum droplet. For this reason, we revisit the theoretical description of quantum fluctuations in dipolar quantum gases. We study alternative cutoffs, compare them to experimental results and discuss limitations.