Observation of three-state dressed states in circuit quantum electrodynamics

TL;DR

This paper reports the experimental observation of three-state dressed states in a transmon qubit coupled to a transmission line, revealing complex microwave responses and confirming theoretical predictions with high accuracy.

Contribution

It demonstrates the formation of three-state dressed states in a transmon qubit, expanding understanding of multi-level quantum state interactions in circuit QED.

Findings

Observation of six Rabi sidebands indicating three-state dressed states

Amplification and attenuation of probe fields due to dressed states

Good agreement between experimental results and theoretical models

Abstract

We have investigated the microwave response of a transmon qubit coupled directly to a transmission line. In a transmon qubit, owing to its weak anharmonicity, a single driving field may generate dressed states involving more than two bare states. We confirmed the formation of three-state dressed states by observing all of the six associated Rabi sidebands, which appear as either amplification or attenuation of the probe field. The experimental results are reproduced with good precision by a theoretical model incorporating the radiative coupling between the qubit and the microwave.