Dresden 2011 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 29: Poster Session: Quantum Information Systems, Quantum Coherence (jointly with SAMOP)

TT 29.3: Poster

Tuesday, March 15, 2011, 18:00–21:00, P1

Decoherence of Josephson junction qubits due to surface spins — •Pablo Schad¹, Boris Narozhny¹, Alexander Shnirman^1,2, and Gerd Schön³ — ¹Institut für Theorie der Kondensierten Materie, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany — ²DFG Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany — ³Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany

Spins on surfaces of superconductors are currently believed to be responsible for the 1/f flux noise in SQUIDs and Josephson qubits [1,2,3,4,5]. In recent experiments the spin contribution to the inductance of superconducting wires was measured [6]. This inductance describes the response to a current, which polarizes spins by creating magnetic fields on the surface. In particular low frequency fluctuations of the complex inductance were observed with roughly a 1/f noise spectrum. We provide an analysis of inductance noise in analogy to the well known theory of "noise of noise" and analyze some microscopic models that could explain these experiments.
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