Floquet interferometry of a dressed semiconductor quantum dot

TL;DR

This paper demonstrates Floquet state dressing in a semiconductor quantum dot, revealing a ladder of hybrid states through high-frequency electrical response, and develops a theory explaining the observed interference phenomena.

Contribution

It introduces the observation of Floquet state dressing in a semiconductor quantum dot and provides a theoretical framework that matches experimental data.

Findings

Observation of Floquet ladder states in a quantum dot

Interference fringes at multiphoton resonances without avoided crossings

Application of technique for quantum dot electrostatic characterization

Abstract

A quantum system interacting with a time-periodic excitation creates a ladder of hybrid eigenstates in which the system is mixed with an increasing number of photons. This mechanism, referred to as dressing, has been observed in the context of light-matter interaction in systems as varied as atoms, molecules and solid-state qubits. In this work, we demonstrate state dressing in a semiconductor quantum dot tunnel-coupled to a charge reservoir. We observe the emergence of a Floquet ladder of states in the system's high-frequency electrical response, manifesting as interference fringes at the multiphoton resonances despite the system lacking an avoided crossing. We study the dressed quantum dot while changing reservoir temperature, charge lifetime, and excitation amplitude and reveal the fundamental nature of the mechanism by developing a theory based on the quantum dynamics of the Floquet ladder, which is in excellent agreement with the data. Furthermore, we show how the technique finds applications in the accurate electrostatic characterisation of semiconductor quantum dots.