Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 103: Transport: Poster Session
TT 103.23: Poster
Donnerstag, 19. März 2015, 15:00–18:00, Poster B
Decoherence in Two-Level Systems — •Sebastian Zanker1, Jürgen Lisenfeld2, Michael Marthaler1, Gerd Schön1, Alexey Ustinov2, and Georg Weiß2 — 1Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology, D-76131 Karlsruhe, Germany — 2Physikalisches Institut, Karlsruhe Institute of Technology , D-76131 Karlsruhe, Germany
We study decoherence of two level systems (TLS) living inside the amorphous AlOx layer of a phase qubit’s Josephson junction. We discuss TLS coupling to phonons, tunneling quasiparticles and other TLS as possible sources of decoherence and compare theoretical decoherence behavior with experimental data. The experiment suggests strong improvements in dephasing times using spin echo protocol as compared to Ramsey dephasing, ΓRamsey/Γecho∼3−55 which indicates a divergent noise spectral density at low frequencies best matched by either other TLS or quasiparticles.