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TT: Fachverband Tiefe Temperaturen

TT 13: Transport: Poster Session

TT 13.44: Poster

Montag, 26. März 2012, 15:00–19:00, Poster B

A strategy to measure the Lamb shift in a superconducting two-level system embedded in a thermal broadband reservoir — •Vera Gramich¹, Paolo Solinas^2,3, Mikko Möttönen^2,3, Jukka Pekola³, and Joachim Ankerhold¹ — ¹Institut für Theoretische Physik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany — ²Department of Applied Physics/COMP, Aalto University, P.O. Box 14100, FI-00076 Aalto, Finland — ³Low Temperature Laboratory, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland

Realistic quantum systems are never completely isolated. Even a single atom in zero-temperature vacuum is influenced by the zero-point fluctuations of the electromagnetic field which in turn induces a shift of its transition frequencies known as the Lamb shift. Cavity quantum electrodynamics (QED) provides a particularly convenient setup to observe this shift since the restricted geometries of the cavities allow the atoms to interact only with the fluctuations of single harmonic fields. In contrast to single-frequency environments, typical reservoirs for mesoscopic solid-state devices are characterized by broadband spectral distributions in thermal equilibrium. Within weak-coupling master equations even explicit expressions for the reservoir-induced frequency shifts can be derived, while associated experimental observations are still missing. To fill this gap, we discuss and analyze a theoretical proposal to retrieve the Lamb shift for a superconducting two-level system embedded in an ohmic environment. Moreover, we present a possible way to measure the Lamb shift in a circuit containing a Cooper pair sluice.