Volume 80, Number 4, November 2007
Article Number 40011
Number of page(s) 5
Section General
Published online 25 October 2007
EPL, 80 (2007) 40011
DOI: 10.1209/0295-5075/80/40011

Crossover from weak- to strong-coupling regime in dispersive circuit QED

I. Serban1, 2, E. Solano1, 3, 4 and F. K. Wilhelm2

1  Physics Department, ASC and CeNS, Ludwig-Maximilians-Universität - Theresienstr. 37, 80333 Munich, Germany
2  IQC and Department of Physics and Astronomy, University of Waterloo - 200 University Ave. W, Waterloo, ON, N2L 3G1, Canada
3  Max-Planck Institute for Quantum Optics - Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany
4  Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú - Apartado 1761, Lima, Peru

received 20 April 2007; accepted in final form 19 September 2007; published November 2007
published online 25 October 2007

We study the decoherence of a superconducting qubit due to the dispersive coupling to a damped harmonic oscillator. We go beyond the weak qubit-oscillator coupling, which we associate with a phase Purcell effect, and enter into a strong coupling regime, with qualitatively different behavior of the dephasing rate. We identify and give a physicaly intuitive discussion of both decoherence mechanisms. Our results can be applied, with small adaptations, to a large variety of other physical systems, e.g. trapped ions and cavity QED, boosting theoretical and experimental decoherence studies.

03.65.Yz - Decoherence; open systems; quantum statistical methods.
85.25.-j - Superconducting devices.
42.50.Pq - Cavity quantum electrodynamics; micromasers.

© Europhysics Letters Association 2007