Berlin 2012 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 46: Superconductivity: Tunnelling, Josephson Junctions, SQUIDs 2

TT 46.6: Vortrag

Donnerstag, 29. März 2012, 19:15–19:30, H 2053

Strain tuning atomic tunneling systems in a Josephson junction — •Grigorij J. Grabovskij, Torben Peichl, Jürgen Lisenfeld, Georg Weiss, and Alexey V. Ustinov — Karlsruhe Institute of Technology, Physikalisches Institut, 76131 Karlsruhe

The so-called tunneling model assumes transitions of atoms between different localized configurations of the disordered structure of the solid. A transition like that is attributed to the two-level system (TLS) formed by the two lowest energy states of atoms tunneling in a double-well potential. The development of superconducting circuits based on Josephson junctions as active elements grants access to single microscopic defect states located inside the disordered tunneling barrier. The spectra of Josephson phase qubits show avoided level crossings corresponding to individual coherent TLSs. We performed an experiment in which a chip with a phase qubit was bent using a piezo actuator. The tiny displacement of atoms on the chip surface, which is estimated to be of the order of the nuclei size, changes the potential of TLSs. We observed a change of the TLS resonance frequency as a function of the strain field that confirms the tunneling model assumptions for TLSs and yields unique data for the TLS potential.