Measurement of Autler-Townes and Mollow transitions in a strongly driven superconducting qubit

TL;DR

This paper reports spectroscopic measurements of Autler-Townes and Mollow spectral features in a strongly driven superconducting qubit, confirming theoretical predictions with high accuracy.

Contribution

It provides the first detailed experimental observation of these phenomena in a superconducting qubit, validating a dispersive Jaynes-Cummings model including higher states.

Findings

Good agreement between observed and predicted spectral lines

Detection of Autler-Townes doublet and Mollow triplet sidebands

Validation of theoretical models with experimental data

Abstract

We present spectroscopic measurements of the Autler-Townes doublet and the sidebands of the Mollow triplet in a driven superconducting qubit. The ground to first excited state transition of the qubit is strongly pumped while the resulting dressed qubit spectrum is probed with a weak tone. The corresponding transitions are detected using dispersive read-out of the qubit coupled off-resonantly to a microwave transmission line resonator. The observed frequencies of the Autler-Townes and Mollow spectral lines are in good agreement with a dispersive Jaynes-Cummings model taking into account higher excited qubit states and dispersive level shifts due to off-resonant drives.