Dynamics of a qubit coupled to a harmonic oscillator

Abstract

We present experimental results showing the coherent dynamics of a flux-qubit coupled to the plasma mode of its measuring DC-SQUID. Resonances corresponding to transitions where both the qubit and the oscillator energy state are changed were observed in the excitation spectrum. We also measured Rabi oscillations on these transitions. We used this coupling to measure the effective temperature of the oscillator and to probe the qubit state after a Rabi oscillation. Our measurements indicate that the intrinsic efficiency of the Rabi pulses is 90%, much larger than the signal visibility (35%). We conclude that this limited visibility is likely due to relaxation during the measurement. © 2006 Springer Science+Business Media, Inc.