Quantum Flutter: Signatures and Robustness

TL;DR

This paper studies quantum flutter, a phenomenon where an impurity in a 1D quantum gas exhibits long-lived oscillations in momentum, revealing insights into excitation spectra and robustness beyond integrable models.

Contribution

It demonstrates the existence of quantum flutter in non-integrable systems and links its frequency to excitation spectrum differences using numerical simulations.

Findings

Quantum flutter persists away from integrability.

Flutter frequency matches energy differences of collective excitations.

Parameter regimes for experimental observation are identified.

Abstract

We investigate the motion of an impurity particle injected with finite velocity into an interacting one-dimensional quantum gas. Using large-scale numerical simulations based on matrix product states, we observe and quantitatively analyze long-lived oscillations of the impurity momentum around a non-zero saturation value, called quantum flutter. We show that the quantum flutter frequency is equal to the energy difference between two branches of collective excitations of the model. We propose an explanation of the finite saturation momentum of the impurity based on the properties of the edge of the excitation spectrum. Our results indicate that quantum flutter exists away from integrability, and provide parameter regions in which it could be observed in experiments with ultracold atoms using currently available technology.