Strong-field effects in the Rabi oscillations of the superconducting phase qubit

TL;DR

This paper investigates the effects of strong microwave drives on Rabi oscillations in superconducting phase qubits, combining theory and experiments to understand high-power behaviors like ac Stark shifts and multi-photon Rabi frequencies.

Contribution

It introduces a three-level multiphoton analysis to accurately describe high-power Rabi oscillations in superconducting phase qubits, validated by experimental data.

Findings

Good agreement between theoretical predictions and experimental measurements.

Analytical and numerical results for ac Stark shift and Rabi frequencies.

Identification of multiphoton effects at high microwave power.

Abstract

Rabi oscillations have been observed in many superconducting devices, and represent prototypical logic operations for quantum bits (qubits) in a quantum computer. We use a three-level multiphoton analysis to understand the behavior of the superconducting phase qubit (current-biased Josephson junction) at high microwave drive power. Analytical and numerical results for the ac Stark shift, single-photon Rabi frequency, and two-photon Rabi frequency are compared to measurements made on a dc SQUID phase qubit with Nb/AlOx/Nb tunnel junctions. Good agreement is found between theory and experiment.