We have performed spectroscopic measurements of a superconducting qubit dispersively coupled to a nonlinear resonator driven by a pump microwave field. Measurements of the qubit frequency shift provide a sensitive probe of the intracavity field, yielding a precise characterization of the resonator nonlinearity. The qubit linewidth has a complex dependence on the pump frequency and amplitude, which is correlated with the gain of the nonlinear resonator operated as a small-signal amplifier. The corresponding dephasing rate is found to be close to the quantum limit in the low-gain limit of the amplifier.
@article{arxiv.1010.6248,
title = {Circuit QED with a Nonlinear Resonator : ac-Stark Shift and Dephasing},
author = {F. R. Ong and M. Boissonneault and F. Mallet and A. Palacios-Laloy and A. Dewes and A. C. Doherty and A. Blais and P. Bertet and D. Vion and D. Esteve},
journal= {arXiv preprint arXiv:1010.6248},
year = {2015}
}
Comments
Paper : 4 pages, 3 figures; Supplementary material : 1 page, 1 figure