Dresden 2009 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 13: Focussed Session: Superconducting Quantum Circuits
TT 13.6: Talk
Tuesday, March 24, 2009, 12:15–12:30, HSZ 03
Phase diffusion in single-qubit lasers — •Stephan André1,2, Valentina Brosco1,2, Alexander Shnirman2,3, and Gerd Schön1,2 — 1Institut für Theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe, Germany — 2DFG Center for Functional Nanostructures (CFN), Universität Karlsruhe, 76128 Karlsruhe, Germany — 3Institut für Theorie der Kondensierten Materie, Universität Karlsruhe, 76128 Karlsruhe, Germany
Recent experiments explored the dynamics of superconducting qubits, playing the role of artificial atoms, coupled to quantum electrical resonators. Single-qubit lasers were realized by creating a population inversion in the qubit [1]. In contrast to conventional lasers, single-qubit lasers are characterized by a strong qubit-oscillator coupling and a richer noise spectrum for the qubit.
We theoretically investigate the spectral properties of single-qubit lasers, focussing on the effects of the strong coupling and of 1/f-noise [2]. Specifically, we show that low-frequency charge fluctuations can explain the inhomogeneous broadening of the spectrum observed in the experiment.
[1] O. Astafiev et al., Nature 449, 588 (2007)
[2] S. André et al., arXiv:0807.4607 (2008)