Multiparticle quantum walk: a dynamical probe of topological many-body excitations

TL;DR

This paper extends quantum walk techniques from single particles to many-body systems, demonstrating that multiparticle quantum walks can reveal topological phases and transitions in strongly interacting fermionic chains, with potential experimental applications.

Contribution

It introduces a method to probe topological properties of many-body excitations via multiparticle quantum walks in interacting fermionic chains, highlighting the robustness of topological signals under interactions and disorder.

Findings

Many-body Berry phase signals topological transitions.

Single- and many-body mean chiral displacement detect topology.

Topological features persist under strong interactions and moderate disorder.

Abstract

Recent experiments demonstrated that single-particle quantum walks can reveal the topological properties of single-particle states. Here, we generalize this picture to the many-body realm by focusing on multiparticle quantum walks of strongly interacting fermions. After injecting $N$ particles with multiple flavors in the interacting SU$(N)$ Su-Schrieffer-Heeger chain, their multiparticle continuous-time quantum walk is monitored by a variety of methods. We find that the many-body Berry phase in the $N$-body part of the spectrum signals a topological transition upon varying the dimerization, similarly to the single-particle case. This topological transition is captured by the single- and many-body mean chiral displacement during the quantum walk and remains present for strong interaction as well as for moderate disorder. Our predictions are well within experimental reach for cold atomic gases and can be used to detect the topological properties of many-body excitations through dynamical probes.