Core-Hole Excitation Dynamics of One-Dimensional Ultracold Trapped Fermions

TL;DR

This study explores the nonequilibrium dynamics of core-hole excitations in a one-dimensional ultracold fermionic system, revealing how various parameters influence impurity-bath interactions and many-body correlations.

Contribution

It combines two ab initio methods to analyze core-hole dynamics, highlighting the robustness of deep core holes and their potential for probing many-body phenomena.

Findings

Deep core holes are more resistant to refilling than bulk or edge vacancies.

Impurity and bath dynamics depend on interaction strength, confinement, and initial hole position.

Many-body correlations build up over time, as shown by von Neumann entropy.

Abstract

We investigate the nonequilibrium dynamics of core-hole excitations in a one-dimensional fermionic few-body system consisting of a spin-polarized Fermi bath coupled to a single heavy mobile impurity. The bath is initially prepared in a particle-hole configuration by emptying a selected bath single-particle orbital, while the impurity is displaced with respect to the center of the bath confinement potential. The quench dynamics are initialized by suddenly switching on the impurity-bath interaction. To resolve the resulting dynamics, we combine two complementary \textit{ab initio} approaches, namely the Multi-Layer Multi-Configuration Time-Dependent Hartree method for mixtures and a multi-channel Born-Oppenheimer framework. We show that the postquench response is governed by the interaction strength, impurity confinement, mass imbalance, and the location of the initially prepared hole within the Fermi sea. The density evolution and impurity center-of-mass motion reveal a competition between mixing and demixing of impurity and bath, while the von Neumann entropy demonstrates the buildup of pronounced many-body correlations. Most importantly, the occupation dynamics of the initially emptied orbital identifies deep core holes as substantially more robust against refilling than bulk or edge vacancies. Our results establish core-hole excitations as robust dynamical many-body features in trapped ultracold fermions and provide a controlled route towards probing orthogonality response, correlation buildup, and hole refilling in real time.