Exciton transport in a germanium quantum dot ladder

TL;DR

This paper demonstrates exciton formation and transport in a germanium quantum dot ladder, using Coulomb interactions and drag effects to transition from single-electron to exciton transport, advancing quantum simulation capabilities.

Contribution

It introduces a method to observe exciton transport in a quantum dot array, leveraging Coulomb drag to study excitonic states in engineered quantum systems.

Findings

Observation of exciton formation via Coulomb drag.

Transition from single-electron to exciton transport.

Potential for quantum simulation of excitonic phenomena.

Abstract

Quantum systems with engineered Hamiltonians can be used as simulators of many-body physics problems to provide insights beyond the capabilities of classical computers. Semiconductor gate-defined quantum dot arrays have emerged as a versatile platform for quantum simulation of generalized Fermi-Hubbard physics, one of the richest playgrounds in condensed matter physics. In this work, we employ a germanium 4$\times$2 quantum dot array and show that the naturally occurring long-range Coulomb interaction can lead to exciton formation and transport. We tune the quantum dot ladder into two capacitively-coupled channels and exploit Coulomb drag to probe the binding of electrons and holes. Specifically, we shuttle an electron through one leg of the ladder and observe that a hole is dragged along in the second leg under the right conditions. This corresponds to a transition from single-electron transport in one leg to exciton transport along the ladder. Our work paves the way for the study of excitonic states of matter in quantum dot arrays.