Domain-wall melting in ultracold boson systems with holes and spin-flip defects

TL;DR

This paper investigates how holes and spin-flip defects affect the dynamics of domain-wall melting in ultracold bosonic systems, using tDMRG simulations, highlighting the different impacts of these imperfections on observable behaviors.

Contribution

It provides a detailed analysis of defect effects on domain-wall melting in bosonic systems, emphasizing the linear shift approximation for holes and the significant impact of spin-flips.

Findings

Holes' effects can be approximated by spatially shifted observables.

For large U, holes have negligible effects.

Spin-flips significantly alter the melting dynamics.

Abstract

Quantum magnetism is a fundamental phenomenon of nature. As of late, it has garnered a lot of interest because experiments with ultracold atomic gases in optical lattices could be used as a simulator for phenomena of magnetic systems. A paradigmatic example is the time evolution of a domain-wall state of a spin-1/2 Heisenberg chain, the so-called domain-wall melting. The model can be implemented by having two species of bosonic atoms with unity filling and strong on-site repulsion U in an optical lattice. In this paper, we study the domain-wall melting in such a setup on the basis of the time-dependent density matrix renormalization group (tDMRG). We are particularly interested in the effects of defects that originate from an imperfect preparation of the initial state. Typical defects are holes (empty sites) and flipped spins. We show that the dominating effects of holes on observables like the spatially resolved magnetization can be taken account of by a linear combination of spatially shifted observables from the clean case. For sufficiently large U, further effects due to holes become negligible. In contrast, the effects of spin flips are more severe as their dynamics occur on the same time scale as that of the domain-wall melting itself. It is hence advisable to avoid preparation schemes that are based on spin-flips.