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TT: Fachverband Tiefe Temperaturen
TT 23: TR: Quantum Coherence and Quantum Information Systems 2
TT 23.5: Talk
Wednesday, March 24, 2010, 15:15–15:30, H18
Spectral properties of single-qubit lasers — •Stephan André1,2, Valentina Brosco3, Alexander Shnirman2,4, and Gerd Schön1,2 — 1Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany — 2DFG Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany — 3Dipartimento di Fisica, Università "La Sapienza", P.le A. Moro 2, 00185 Roma, Italy — 4Institut für Theorie der Kondensierten Materie, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany
Recent experiments demonstrated lasing and cooling of the electromagnetic field in an electrical resonator coupled to a superconducting qubit [1]. In this work, we theoretically investigate the spectral properties of single-qubit lasers by numerically solving the full Liouville equation for the density matrix. We extend the usual quantum optics description to acccount for strong qubit-resonator coupling and to include the effects of low-frequency noise.
We present results for the linewidth and the lineshape of the emission spectrum. We find that the linewidth grows with the qubit-resonator coupling strength beyond the lasing transition, thus deteriorating the lasing state [2]. Our results also show that quantum correlations have a significant effect on the spectral properties and that low-frequency noise might explain the shape and width of the emission spectrum observed in the experiment.
[1] O. Astafiev et al., Nature 449, 588 (2007)
[2] S. André et al., arXiv:0908.4227 (2009)