Self-consistent effective field theory to nonuniversal Lee-Huang-Yang term in quantum droplets

TL;DR

This paper develops a self-consistent effective field theory to incorporate finite-range interactions in quantum droplets, revealing nonuniversal Lee-Huang-Yang terms and predicting measurable effects on collective modes.

Contribution

It introduces a novel analytical EOS for bosonic mixtures with finite-range interactions, bridging the gap between simplified models and real atomic potentials.

Findings

Finite-range interactions significantly modify quantum droplet mechanics.

Nonuniversal LHY terms encode short-range interaction details.

Predicted fractional frequency shifts in breathing modes are experimentally observable.

Abstract

Quantum droplets (QDs) in weakly interacting ultracold quantum gases are typically characterized by mean-field theories incorporating Lee-Huang-Yang (LHY) quantum fluctuations under simplified zero-range interaction assumptions. However, bridging these models to broader physical regimes like superfluid helium requires precise understanding of short-range interatomic interactions. Here, we investigate how finite-range interactions--next-order corrections to zero-range potentials--significantly alter QDs mechanics. Using a consistent effective theory, we derive an analytical equation of state (EOS) for three-dimensional bosonic mixtures under finite-range interactions at zero temperature. Leveraging the Hubbard-Stratonovich transformation, we demonstrate that interspecies attraction facilitates bosonic pairing across components characterized by the non-perturbative parameter of $\Delta$, leading to nonuniversal LHY terms that encode short-range interaction details while recovering previous universal QDs EOS in the zero-range limit. Extending superfluid hydrodynamic equations for two-component systems, we predict fractional frequency shifts in breathing modes induced by these nonuniversal terms. Experimental observation of these shifts would reveal critical insights into QDs dynamics and interatomic potential characteristics.