2010/10/31 by F. R. Ong, M. Boissonneault, F. Mallet +7 · 1 citation
Physics and Astronomy · #cond-mat.mes-hall #quant-ph
paper · pdf · doi:10.1103/physrevlett.106.167002
published as Phys. Rev. Lett. 106, 167002 (2011) · Paper : 4 pages, 3 figures; Supplementary material : 1 page, 1 figure
arxiv created 2011/04/27 · arxiv updated 2015/03/17
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.