Interaction quenches in Bose gases studied with a time-dependent hypernetted-chain Euler-Lagrange method

TL;DR

This paper introduces a new variational method called tHNC for studying the dynamics of bosonic many-body systems, effectively capturing quantum fluctuations and applicable across multiple dimensions, with specific focus on interaction quenches in Bose gases.

Contribution

The paper presents the tHNC method, a non-perturbative variational approach based on the Jastrow ansatz, capable of analyzing dynamics in 1D, 2D, and 3D Bose gases during interaction quenches.

Findings

tHNC accurately models quantum fluctuations in Bose gases.

Stable oscillations in pair distribution functions occur after strong quenches with roton excitations.

Validation against variational Monte Carlo confirms the method's reliability.

Abstract

We present a new variational method to study the dynamics of a closed bosonic many-body system, the time-dependent hypernetted-chain Euler-Lagrange method, tHNC . Based on the Jastrow ansatz, it accounts for quantum fluctuations in a non-perturbative way. tHNC scales well with the number of dimensions, as demonstrated by our results on one, two, and three dimensions. We apply the tHNC method to interaction quenches, i.e. sudden changes of the interaction strength, in homogeneous Bose gases. When the quench is strong enough that the final state has roton excitations (as found and predicted for dipolar and Rydberg-dressed Bose-Einstein condensates, respectively), the pair distribution function exhibits stable oscillations. For validation, we compare tHNC results with time-dependent variational Monte Carlo results in one and two dimensions.