Sideband Transitions and Two-Tone Spectroscopy of a Superconducting Qubit Strongly Coupled to an On-Chip Cavity

TL;DR

This paper investigates sideband transitions in a superconducting qubit coupled to a cavity, demonstrating large ac-Stark shifts and exploring their implications for quantum information processing.

Contribution

It provides experimental observation and theoretical analysis of sideband transitions in a strongly coupled superconducting qubit-cavity system at the optimal charge bias point.

Findings

Large dispersive ac-Stark shifts observed

Sideband transitions require two-photon processes at optimal bias

Results align well with theoretical predictions

Abstract

Sideband transitions are spectroscopically probed in a system consisting of a Cooper pair box strongly but non-resonantly coupled to a superconducting transmission line resonator. When the Cooper pair box is operated at the optimal charge bias point the symmetry of the hamiltonian requires a two photon process to access sidebands. The observed large dispersive ac-Stark shifts in the sideband transitions induced by the strong non-resonant drives agree well with our theoretical predictions. Sideband transitions are important in realizing qubit-photon and qubit-qubit entanglement in the circuit quantum electrodynamics architecture for quantum information processing.