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Q: Fachverband Quantenoptik und Photonik

Q 3: Photonics I

Q 3.3: Vortrag

Montag, 10. März 2025, 11:45–12:00, HS Botanik

Quantum theory of (fractional) topological transport of lattice solitons — •Julius Bohm, Hugo Gerlitz, and Michael Fleischhauer — Fachbereich Physik und Landesforschungszentrum OPTIMAS, RPTU Kaiserslautern-Landau

Thouless pumps are a well known concept for quantized transport in symmetry protected topological systems. A suitable platform to investigate those systems are ultracold atoms in (time-dependent) lattices. While the experiments show good agreement with the theory they are hard to control and costly.

In recent years experimental groups have been able to investigate lattice solitons in waveguides with nonlinear Kerr media [1]. The time dependency needed for Thouless pumping in such systems is simulated via spatial modulation of the waveguides along the propagation axis.

On the theoretical side these solitons have been considered so far from a semiclassical point of view [2]. In our research we extend this to a full quantum mechanical description and therefore are able to test the low-particle limits in which lattice solitons exist. We are able to simulate integer as well as fractional transport of lattice solitons with the help of exact diagonalization and tensor network based approaches. Furthermore the emergence of integer, fractional and localized phases is explained in terms of an effective soliton bandstructure which also allows to determine topological invariants as effective Chern numbers or Wilson loops.

[1]: Jürgensen et. al., Nature 596, 63-67 (2021)

[2]: Mostaan et. al., Nat Commun 13, 5997 (2022)

Keywords: Topology; Waveguides; Kerr Effect; Nonlinear; Soliton