Quenched dynamics of the momentum distribution of the unitary Bose gas

TL;DR

This paper investigates the real-time evolution of the momentum distribution in a unitary Bose gas under harmonic confinement after a sudden increase in interaction strength, using a density functional approach informed by Monte Carlo data.

Contribution

It introduces a time-dependent density functional method to study quenched dynamics of a unitary Bose gas, connecting theoretical predictions with recent experimental observations.

Findings

Low-momentum distribution reaches a quasi-stationary state after a long transient.

High-momentum components equilibrate faster than three-body loss times.

Results align with recent experimental data on $^{85}$Rb atoms at unitarity.

Abstract

We study the quenched dynamics of the momentum distribution of a unitary Bose gas under isotropic harmonic confinement within a time-dependent density functional approach based on our recently calculated Monte Carlo (MC) bulk equation of state. In our calculations the inter-atomic s-wave scattering length of the trapped bosons is suddenly increased to a very large value and the real-time evolution of the system is studied. Prompted by the very recent experimental data of $^{85}$Rb atoms at unitarity [Nature Phys. 10, 116 (2014)] we focus on the momentum distribution as a function of time. Our results suggest that at low momenta, a quasi-stationary momentum distribution is reached after a long transient, contrary to what found experimentally for large momenta which equilibrate on a time scale shorter than the one for three body losses.