Site-resolved magnon and triplon dynamics on a programmable quantum dot spin ladder

TL;DR

This paper demonstrates the use of germanium quantum dot arrays to simulate and analyze the dynamics of magnons and triplons, including the effects of disorder, providing insights into quantum many-body phenomena.

Contribution

It introduces a novel methodology combining digital and analog quantum operations to study spin excitation dynamics in quantum dot systems.

Findings

Reconstructed quantum walk plots for magnons and triplons.

Explored the impact of single-site disorder on spin excitation propagation.

Provided a platform for simulating disorder-induced phenomena like many-body localization.

Abstract

Quasi-particle dynamics in interacting systems in the presence of disorder challenges the notion of internal thermalization, but proves difficult to investigate theoretically for large particle numbers. Engineered quantum systems may offer a viable alternative, as witnessed in experimental demonstrations in a variety of physical platforms, each with its own capabilities and limitations. Semiconductor gate-defined quantum dot arrays are of particular interest since they offer both a direct mapping of their Hamiltonian to Fermi-Hubbard and Heisenberg models and the in-situ tunability of (magnetic) interactions and onsite potentials. In this work, we use an array of germanium quantum dots to simulate the dynamics of both single-spin excitations (magnons) and two-spin excitations (triplons). We develop a methodology that combines digital spin qubit operations for state preparation and readout with analog evolution under the full system Hamiltonian. Using these techniques, we can reconstruct quantum walk plots for both magnons and triplons, and for various configurations of Heisenberg exchange couplings. We furthermore explore the effect of single-site disorder and its impact on the propagation of spin excitations. The obtained results can provide a basis for simulating disorder-based solid-state phenomena such as many-body localization.